ref: 4faecc77264b6d3e84ae24707af5593490f36796
parent: 6ea453c95f1051b23bc128a34e1166bc9c53cdff
author: Simon Tatham <anakin@pobox.com>
date: Fri Oct 21 04:07:31 EDT 2005
New puzzle from James H: `Bridges', another Nikoli job. [originally from svn r6409]
--- a/Recipe
+++ b/Recipe
@@ -26,11 +26,12 @@
MAP = map dsf
LOOPY = loopy tree234 dsf
LIGHTUP = lightup combi
-TENTS = tents maxflow
+TENTS = tents maxflow
+BRIDGES = bridges dsf
ALL = list NET NETSLIDE cube fifteen sixteen rect pattern solo twiddle
+ MINES samegame FLIP guess PEGS dominosa UNTANGLE blackbox SLANT
- + LIGHTUP MAP LOOPY inertia TENTS
+ + LIGHTUP MAP LOOPY inertia TENTS BRIDGES
GTK = gtk printing ps
@@ -57,6 +58,7 @@
loopy : [X] GTK COMMON LOOPY
inertia : [X] GTK COMMON inertia
tents : [X] GTK COMMON TENTS
+bridges : [X] GTK COMMON BRIDGES
# Auxiliary command-line programs.
STANDALONE = nullfe random misc malloc
@@ -102,6 +104,7 @@
loopy : [G] WINDOWS COMMON LOOPY
inertia : [G] WINDOWS COMMON inertia
tents : [G] WINDOWS COMMON TENTS
+bridges : [G] WINDOWS COMMON BRIDGES
# Mac OS X unified application containing all the puzzles.
Puzzles : [MX] osx osx.icns osx-info.plist COMMON ALL
@@ -194,7 +197,7 @@
for i in cube net netslide fifteen sixteen twiddle \
pattern rect solo mines samegame flip guess \
pegs dominosa untangle blackbox slant lightup \
- map loopy inertia tents; do \
+ map loopy inertia tents bridges; do \
$(INSTALL_PROGRAM) -m 755 $$i $(DESTDIR)$(gamesdir)/$$i \
|| exit 1; \
done
--- /dev/null
+++ b/bridges.c
@@ -1,0 +1,2674 @@
+/*
+ * bridges.c: Implementation of the Nikoli game 'Bridges'.
+ *
+ * Things still to do:
+ *
+ * * write a recursive solver?
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <ctype.h>
+#include <math.h>
+
+#include "puzzles.h"
+
+/* Turn this on for hints about which lines are considered possibilities. */
+#undef DRAW_HINTS
+#undef DRAW_GRID
+#undef DRAW_DSF
+
+/* --- structures for params, state, etc. --- */
+
+#define MAX_BRIDGES 4
+
+#define PREFERRED_TILE_SIZE 24
+#define TILE_SIZE (ds->tilesize)
+#define BORDER (TILE_SIZE / 2)
+
+#define COORD(x) ( (x) * TILE_SIZE + BORDER )
+#define FROMCOORD(x) ( ((x) - BORDER + TILE_SIZE) / TILE_SIZE - 1 )
+
+#define FLASH_TIME 0.50F
+
+enum {+ COL_BACKGROUND,
+ COL_FOREGROUND,
+ COL_HIGHLIGHT, COL_LOWLIGHT,
+ COL_SELECTED, COL_MARK,
+ COL_HINT, COL_GRID,
+ COL_WARNING,
+ NCOLOURS
+};
+
+struct game_params {+ int w, h, maxb;
+ int islands, expansion; /* %age of island squares, %age chance of expansion */
+ int allowloops, difficulty;
+};
+
+/* general flags used by all structs */
+#define G_ISLAND 0x0001
+#define G_LINEV 0x0002 /* contains a vert. line */
+#define G_LINEH 0x0004 /* contains a horiz. line (mutex with LINEV) */
+#define G_LINE (G_LINEV|G_LINEH)
+#define G_MARKV 0x0008
+#define G_MARKH 0x0010
+#define G_MARK (G_MARKV|G_MARKH)
+#define G_NOLINEV 0x0020
+#define G_NOLINEH 0x0040
+#define G_NOLINE (G_NOLINEV|G_NOLINEH)
+
+/* flags used by the drawstate */
+#define G_ISSEL 0x0080
+#define G_REDRAW 0x0100
+#define G_FLASH 0x0200
+#define G_WARN 0x0400
+
+/* flags used by the solver etc. */
+#define G_SWEEP 0x0800
+
+#define G_FLAGSH (G_LINEH|G_MARKH|G_NOLINEH)
+#define G_FLAGSV (G_LINEV|G_MARKV|G_NOLINEV)
+
+typedef unsigned int grid_type; /* change me later if we invent > 16 bits of flags. */
+
+struct solver_state {+ int *dsf, *tmpdsf;
+ int refcount;
+};
+
+/* state->gridi is an optimisation; it stores the pointer to the island
+ * structs indexed by (x,y). It's not strictly necessary (we could use
+ * find234 instead), but Purify showed that board generation (mostly the solver)
+ * was spending 60% of its time in find234. */
+
+struct surrounds { /* cloned from lightup.c */+ struct { int x, y, dx, dy, off; } points[4];+ int npoints, nislands;
+};
+
+struct island {+ game_state *state;
+ int x, y, count;
+ struct surrounds adj;
+};
+
+struct game_state {+ int w, h, completed, solved, allowloops, maxb;
+ grid_type *grid, *scratch;
+ struct island *islands;
+ int n_islands, n_islands_alloc;
+ game_params params; /* used by the aux solver. */
+#define N_WH_ARRAYS 5
+ char *wha, *possv, *possh, *lines, *maxv, *maxh;
+ struct island **gridi;
+ struct solver_state *solver; /* refcounted */
+};
+
+#define GRIDSZ(s) ((s)->w * (s)->h * sizeof(grid_type))
+
+#define INGRID(s,x,y) ((x) >= 0 && (x) < (s)->w && (y) >= 0 && (y) < (s)->h)
+
+#define DINDEX(x,y) ((y)*state->w + (x))
+
+#define INDEX(s,g,x,y) ((s)->g[(y)*((s)->w) + (x)])
+#define IDX(s,g,i) ((s)->g[(i)])
+#define GRID(s,x,y) INDEX(s,grid,x,y)
+#define SCRATCH(s,x,y) INDEX(s,scratch,x,y)
+#define POSSIBLES(s,dx,x,y) ((dx) ? (INDEX(s,possh,x,y)) : (INDEX(s,possv,x,y)))
+#define MAXIMUM(s,dx,x,y) ((dx) ? (INDEX(s,maxh,x,y)) : (INDEX(s,maxv,x,y)))
+
+#define GRIDCOUNT(s,x,y,f) ((GRID(s,x,y) & (f)) ? (INDEX(s,lines,x,y)) : 0)
+
+#define WITHIN2(x,min,max) (((x) < (min)) ? 0 : (((x) > (max)) ? 0 : 1))
+#define WITHIN(x,min,max) ((min) > (max) ? \
+ WITHIN2(x,max,min) : WITHIN2(x,min,max))
+
+/* --- island struct and tree support functions --- */
+
+#define ISLAND_ORTH(is,j,f,df) \
+ (is->f + (is->adj.points[(j)].off*is->adj.points[(j)].df))
+
+#define ISLAND_ORTHX(is,j) ISLAND_ORTH(is,j,x,dx)
+#define ISLAND_ORTHY(is,j) ISLAND_ORTH(is,j,y,dy)
+
+static void fixup_islands_for_realloc(game_state *state)
+{+ int i;
+
+ for (i = 0; i < state->w*state->h; i++) state->gridi[i] = NULL;
+ for (i = 0; i < state->n_islands; i++) {+ struct island *is = &state->islands[i];
+ is->state = state;
+ INDEX(state, gridi, is->x, is->y) = is;
+ }
+}
+
+static char *game_text_format(game_state *state)
+{+ int x, y, len, nl;
+ char *ret, *p;
+ struct island *is;
+ grid_type grid;
+
+ len = (state->h) * (state->w+1) + 1;
+ ret = snewn(len, char);
+ p = ret;
+
+ for (y = 0; y < state->h; y++) {+ for (x = 0; x < state->w; x++) {+ grid = GRID(state,x,y);
+ nl = INDEX(state,lines,x,y);
+ is = INDEX(state, gridi, x, y);
+ if (is) {+ *p++ = '0' + is->count;
+ } else if (grid & G_LINEV) {+ *p++ = (nl > 1) ? '"' : (nl == 1) ? '|' : '!'; /* gaah, want a double-bar. */
+ } else if (grid & G_LINEH) {+ *p++ = (nl > 1) ? '=' : (nl == 1) ? '-' : '~';
+ } else {+ *p++ = '.';
+ }
+ }
+ *p++ = '\n';
+ }
+ *p++ = '\0';
+
+ assert(p - ret == len);
+ return ret;
+}
+
+static void debug_state(game_state *state)
+{+ char *textversion = game_text_format(state);
+ debug(("%s", textversion));+ sfree(textversion);
+}
+
+/*static void debug_possibles(game_state *state)
+{+ int x, y;
+ debug(("possh followed by possv\n"));+ for (y = 0; y < state->h; y++) {+ for (x = 0; x < state->w; x++) {+ debug(("%d", POSSIBLES(state, 1, x, y)));+ }
+ debug((" "));+ for (x = 0; x < state->w; x++) {+ debug(("%d", POSSIBLES(state, 0, x, y)));+ }
+ debug(("\n"));+ }
+ debug(("\n"));+ for (y = 0; y < state->h; y++) {+ for (x = 0; x < state->w; x++) {+ debug(("%d", MAXIMUM(state, 1, x, y)));+ }
+ debug((" "));+ for (x = 0; x < state->w; x++) {+ debug(("%d", MAXIMUM(state, 0, x, y)));+ }
+ debug(("\n"));+ }
+ debug(("\n"));+}*/
+
+static void island_set_surrounds(struct island *is)
+{+ assert(INGRID(is->state,is->x,is->y));
+ is->adj.npoints = is->adj.nislands = 0;
+#define ADDPOINT(cond,ddx,ddy) do {\+ if (cond) { \+ is->adj.points[is->adj.npoints].x = is->x+(ddx); \
+ is->adj.points[is->adj.npoints].y = is->y+(ddy); \
+ is->adj.points[is->adj.npoints].dx = (ddx); \
+ is->adj.points[is->adj.npoints].dy = (ddy); \
+ is->adj.points[is->adj.npoints].off = 0; \
+ is->adj.npoints++; \
+ } } while(0)
+ ADDPOINT(is->x > 0, -1, 0);
+ ADDPOINT(is->x < (is->state->w-1), +1, 0);
+ ADDPOINT(is->y > 0, 0, -1);
+ ADDPOINT(is->y < (is->state->h-1), 0, +1);
+}
+
+static void island_find_orthogonal(struct island *is)
+{+ /* fills in the rest of the 'surrounds' structure, assuming
+ * all other islands are now in place. */
+ int i, x, y, dx, dy, off;
+
+ is->adj.nislands = 0;
+ for (i = 0; i < is->adj.npoints; i++) {+ dx = is->adj.points[i].dx;
+ dy = is->adj.points[i].dy;
+ x = is->x + dx;
+ y = is->y + dy;
+ off = 1;
+ is->adj.points[i].off = 0;
+ while (INGRID(is->state, x, y)) {+ if (GRID(is->state, x, y) & G_ISLAND) {+ is->adj.points[i].off = off;
+ is->adj.nislands++;
+ /*debug(("island (%d,%d) has orth is. %d*(%d,%d) away at (%d,%d).\n",+ is->x, is->y, off, dx, dy,
+ ISLAND_ORTHX(is,i), ISLAND_ORTHY(is,i)));*/
+ goto foundisland;
+ }
+ off++; x += dx; y += dy;
+ }
+foundisland:
+ ;
+ }
+}
+
+static int island_hasbridge(struct island *is, int direction)
+{+ int x = is->adj.points[direction].x;
+ int y = is->adj.points[direction].y;
+ grid_type gline = is->adj.points[direction].dx ? G_LINEH : G_LINEV;
+
+ if (GRID(is->state, x, y) & gline) return 1;
+ return 0;
+}
+
+static struct island *island_find_connection(struct island *is, int adjpt)
+{+ struct island *is_r;
+
+ assert(adjpt < is->adj.npoints);
+ if (!is->adj.points[adjpt].off) return NULL;
+ if (!island_hasbridge(is, adjpt)) return NULL;
+
+ is_r = INDEX(is->state, gridi,
+ ISLAND_ORTHX(is, adjpt), ISLAND_ORTHY(is, adjpt));
+ assert(is_r);
+
+ return is_r;
+}
+
+static struct island *island_add(game_state *state, int x, int y, int count)
+{+ struct island *is;
+ int realloced = 0;
+
+ assert(!(GRID(state,x,y) & G_ISLAND));
+ GRID(state,x,y) |= G_ISLAND;
+
+ state->n_islands++;
+ if (state->n_islands > state->n_islands_alloc) {+ state->n_islands_alloc = state->n_islands * 2;
+ state->islands =
+ sresize(state->islands, state->n_islands_alloc, struct island);
+ realloced = 1;
+ }
+ is = &state->islands[state->n_islands-1];
+
+ memset(is, 0, sizeof(struct island));
+ is->state = state;
+ is->x = x;
+ is->y = y;
+ is->count = count;
+ island_set_surrounds(is);
+
+ if (realloced)
+ fixup_islands_for_realloc(state);
+ else
+ INDEX(state, gridi, x, y) = is;
+
+ return is;
+}
+
+
+/* n = -1 means 'flip NOLINE flags [and set line to 0].' */
+static void island_join(struct island *i1, struct island *i2, int n, int is_max)
+{+ game_state *state = i1->state;
+ int s, e, x, y;
+
+ assert(i1->state == i2->state);
+ assert(n >= -1 && n <= i1->state->maxb);
+
+ if (i1->x == i2->x) {+ x = i1->x;
+ if (i1->y < i2->y) {+ s = i1->y+1; e = i2->y-1;
+ } else {+ s = i2->y+1; e = i1->y-1;
+ }
+ for (y = s; y <= e; y++) {+ if (is_max) {+ INDEX(state,maxv,x,y) = n;
+ } else {+ if (n < 0) {+ GRID(state,x,y) ^= G_NOLINEV;
+ } else if (n == 0) {+ GRID(state,x,y) &= ~G_LINEV;
+ } else {+ GRID(state,x,y) |= G_LINEV;
+ INDEX(state,lines,x,y) = n;
+ }
+ }
+ }
+ } else if (i1->y == i2->y) {+ y = i1->y;
+ if (i1->x < i2->x) {+ s = i1->x+1; e = i2->x-1;
+ } else {+ s = i2->x+1; e = i1->x-1;
+ }
+ for (x = s; x <= e; x++) {+ if (is_max) {+ INDEX(state,maxh,x,y) = n;
+ } else {+ if (n < 0) {+ GRID(state,x,y) ^= G_NOLINEH;
+ } else if (n == 0) {+ GRID(state,x,y) &= ~G_LINEH;
+ } else {+ GRID(state,x,y) |= G_LINEH;
+ INDEX(state,lines,x,y) = n;
+ }
+ }
+ }
+ } else {+ assert(!"island_join: islands not orthogonal.");
+ }
+}
+
+/* Counts the number of bridges currently attached to the island. */
+static int island_countbridges(struct island *is)
+{+ int i, c = 0;
+
+ for (i = 0; i < is->adj.npoints; i++) {+ c += GRIDCOUNT(is->state,
+ is->adj.points[i].x, is->adj.points[i].y,
+ is->adj.points[i].dx ? G_LINEH : G_LINEV);
+ }
+ /*debug(("island count for (%d,%d) is %d.\n", is->x, is->y, c));*/+ return c;
+}
+
+static int island_adjspace(struct island *is, int marks, int missing,
+ int direction)
+{+ int x, y, poss, curr, dx;
+ grid_type gline, mline;
+
+ x = is->adj.points[direction].x;
+ y = is->adj.points[direction].y;
+ dx = is->adj.points[direction].dx;
+ gline = dx ? G_LINEH : G_LINEV;
+
+ if (marks) {+ mline = dx ? G_MARKH : G_MARKV;
+ if (GRID(is->state,x,y) & mline) return 0;
+ }
+ poss = POSSIBLES(is->state, dx, x, y);
+ poss = min(poss, missing);
+
+ curr = GRIDCOUNT(is->state, x, y, gline);
+ poss = min(poss, MAXIMUM(is->state, dx, x, y) - curr);
+
+ return poss;
+}
+
+/* Counts the number of bridge spaces left around the island;
+ * expects the possibles to be up-to-date. */
+static int island_countspaces(struct island *is, int marks)
+{+ int i, c = 0, missing;
+
+ missing = is->count - island_countbridges(is);
+ if (missing < 0) return 0;
+
+ for (i = 0; i < is->adj.npoints; i++) {+ c += island_adjspace(is, marks, missing, i);
+ }
+ return c;
+}
+
+static int island_isadj(struct island *is, int direction)
+{+ int x, y;
+ grid_type gline, mline;
+
+ x = is->adj.points[direction].x;
+ y = is->adj.points[direction].y;
+
+ mline = is->adj.points[direction].dx ? G_MARKH : G_MARKV;
+ gline = is->adj.points[direction].dx ? G_LINEH : G_LINEV;
+ if (GRID(is->state, x, y) & mline) {+ /* If we're marked (i.e. the thing to attach to is complete)
+ * only count an adjacency if we're already attached. */
+ return GRIDCOUNT(is->state, x, y, gline);
+ } else {+ /* If we're unmarked, count possible adjacency iff it's
+ * flagged as POSSIBLE. */
+ return POSSIBLES(is->state, is->adj.points[direction].dx, x, y);
+ }
+ return 0;
+}
+
+/* Counts the no. of possible adjacent islands (including islands
+ * we're already connected to). */
+static int island_countadj(struct island *is)
+{+ int i, nadj = 0;
+
+ for (i = 0; i < is->adj.npoints; i++) {+ if (island_isadj(is, i)) nadj++;
+ }
+ return nadj;
+}
+
+static void island_togglemark(struct island *is)
+{+ int i, j, x, y, o;
+ struct island *is_loop;
+
+ /* mark the island... */
+ GRID(is->state, is->x, is->y) ^= G_MARK;
+
+ /* ...remove all marks on non-island squares... */
+ for (x = 0; x < is->state->w; x++) {+ for (y = 0; y < is->state->h; y++) {+ if (!(GRID(is->state, x, y) & G_ISLAND))
+ GRID(is->state, x, y) &= ~G_MARK;
+ }
+ }
+
+ /* ...and add marks to squares around marked islands. */
+ for (i = 0; i < is->state->n_islands; i++) {+ is_loop = &is->state->islands[i];
+ if (!(GRID(is_loop->state, is_loop->x, is_loop->y) & G_MARK))
+ continue;
+
+ for (j = 0; j < is_loop->adj.npoints; j++) {+ /* if this direction takes us to another island, mark all
+ * squares between the two islands. */
+ if (!is_loop->adj.points[j].off) continue;
+ assert(is_loop->adj.points[j].off > 1);
+ for (o = 1; o < is_loop->adj.points[j].off; o++) {+ GRID(is_loop->state,
+ is_loop->x + is_loop->adj.points[j].dx*o,
+ is_loop->y + is_loop->adj.points[j].dy*o) |=
+ is_loop->adj.points[j].dy ? G_MARKV : G_MARKH;
+ }
+ }
+ }
+}
+
+static int island_impossible(struct island *is, int strict)
+{+ int curr = island_countbridges(is), nspc = is->count - curr, nsurrspc;
+ int i, poss;
+ grid_type v;
+ struct island *is_orth;
+
+ if (nspc < 0) {+ debug(("island at (%d,%d) impossible because full.\n", is->x, is->y));+ return 1; /* too many bridges */
+ } else if ((curr + island_countspaces(is, 0)) < is->count) {+ debug(("island at (%d,%d) impossible because not enough spaces.\n", is->x, is->y));+ return 1; /* impossible to create enough bridges */
+ } else if (strict && curr < is->count) {+ debug(("island at (%d,%d) impossible because locked.\n", is->x, is->y));+ return 1; /* not enough bridges and island is locked */
+ }
+
+ /* Count spaces in surrounding islands. */
+ nsurrspc = 0;
+ for (i = 0; i < is->adj.npoints; i++) {+ int ifree, dx = is->adj.points[i].dx;
+
+ if (!is->adj.points[i].off) continue;
+ v = GRID(is->state, is->adj.points[i].x, is->adj.points[i].y);
+ poss = POSSIBLES(is->state, dx,
+ is->adj.points[i].x, is->adj.points[i].y);
+ if (poss == 0) continue;
+ is_orth = INDEX(is->state, gridi,
+ ISLAND_ORTHX(is,i), ISLAND_ORTHY(is,i));
+ assert(is_orth);
+
+ ifree = is_orth->count - island_countbridges(is_orth);
+ if (ifree > 0)
+ nsurrspc += min(ifree, MAXIMUM(is->state, dx,
+ is->adj.points[i].x, is->adj.points[i].y));
+ }
+ if (nsurrspc < nspc) {+ debug(("island at (%d,%d) impossible: surr. islands %d spc, need %d.\n",+ is->x, is->y, nsurrspc, nspc));
+ return 1; /* not enough spaces around surrounding islands to fill this one. */
+ }
+
+ return 0;
+}
+
+/* --- Game parameter functions --- */
+
+#define DEFAULT_PRESET 0
+
+const struct game_params bridges_presets[] = {+ { 7, 7, 2, 30, 10, 1, 0 },+ { 7, 7, 2, 30, 10, 1, 1 },+ { 7, 7, 2, 30, 10, 1, 2 },+ { 10, 10, 2, 30, 10, 1, 0 },+ { 10, 10, 2, 30, 10, 1, 1 },+ { 10, 10, 2, 30, 10, 1, 2 },+ { 15, 15, 2, 30, 10, 1, 0 },+ { 15, 15, 2, 30, 10, 1, 1 },+ { 15, 15, 2, 30, 10, 1, 2 },+};
+
+static game_params *default_params(void)
+{+ game_params *ret = snew(game_params);
+ *ret = bridges_presets[DEFAULT_PRESET];
+
+ return ret;
+}
+
+static int game_fetch_preset(int i, char **name, game_params **params)
+{+ game_params *ret;
+ char buf[80];
+
+ if (i < 0 || i >= lenof(bridges_presets))
+ return FALSE;
+
+ ret = default_params();
+ *ret = bridges_presets[i];
+ *params = ret;
+
+ sprintf(buf, "%dx%d %s", ret->w, ret->h,
+ ret->difficulty == 0 ? "easy" :
+ ret->difficulty == 1 ? "medium" : "hard");
+ *name = dupstr(buf);
+
+ return TRUE;
+}
+
+static void free_params(game_params *params)
+{+ sfree(params);
+}
+
+static game_params *dup_params(game_params *params)
+{+ game_params *ret = snew(game_params);
+ *ret = *params; /* structure copy */
+ return ret;
+}
+
+#define EATNUM(x) do { \+ (x) = atoi(string); \
+ while (*string && isdigit((unsigned char)*string)) string++; \
+} while(0)
+
+static void decode_params(game_params *params, char const *string)
+{+ EATNUM(params->w);
+ params->h = params->w;
+ if (*string == 'x') {+ string++;
+ EATNUM(params->h);
+ }
+ if (*string == 'i') {+ string++;
+ EATNUM(params->islands);
+ }
+ if (*string == 'e') {+ string++;
+ EATNUM(params->expansion);
+ }
+ if (*string == 'm') {+ string++;
+ EATNUM(params->maxb);
+ }
+ params->allowloops = 1;
+ if (*string == 'L') {+ string++;
+ params->allowloops = 0;
+ }
+ if (*string == 'd') {+ string++;
+ EATNUM(params->difficulty);
+ }
+}
+
+static char *encode_params(game_params *params, int full)
+{+ char buf[80];
+
+ if (full) {+ sprintf(buf, "%dx%di%de%dm%d%sd%d",
+ params->w, params->h, params->islands, params->expansion,
+ params->maxb, params->allowloops ? "" : "L",
+ params->difficulty);
+ } else {+ sprintf(buf, "%dx%dm%d%s", params->w, params->h,
+ params->maxb, params->allowloops ? "" : "L");
+ }
+ return dupstr(buf);
+}
+
+static config_item *game_configure(game_params *params)
+{+ config_item *ret;
+ char buf[80];
+
+ ret = snewn(8, config_item);
+
+ ret[0].name = "Width";
+ ret[0].type = C_STRING;
+ sprintf(buf, "%d", params->w);
+ ret[0].sval = dupstr(buf);
+ ret[0].ival = 0;
+
+ ret[1].name = "Height";
+ ret[1].type = C_STRING;
+ sprintf(buf, "%d", params->h);
+ ret[1].sval = dupstr(buf);
+ ret[1].ival = 0;
+
+ ret[2].name = "Difficulty";
+ ret[2].type = C_CHOICES;
+ ret[2].sval = ":Easy:Medium:Hard";
+ ret[2].ival = params->difficulty;
+
+ ret[3].name = "Allow loops";
+ ret[3].type = C_BOOLEAN;
+ ret[3].sval = NULL;
+ ret[3].ival = params->allowloops;
+
+ ret[4].name = "Max. bridges per direction";
+ ret[4].type = C_CHOICES;
+ ret[4].sval = ":1:2:3:4"; /* keep up-to-date with MAX_BRIDGES */
+ ret[4].ival = params->maxb - 1;
+
+ ret[5].name = "%age of island squares";
+ ret[5].type = C_CHOICES;
+ ret[5].sval = ":5%:10%:15%:20%:25%:30%";
+ ret[5].ival = (params->islands / 5)-1;
+
+ ret[6].name = "Expansion factor (%age)";
+ ret[6].type = C_CHOICES;
+ ret[6].sval = ":0%:10%:20%:30%:40%:50%:60%:70%:80%:90%:100%";
+ ret[6].ival = params->expansion / 10;
+
+ ret[7].name = NULL;
+ ret[7].type = C_END;
+ ret[7].sval = NULL;
+ ret[7].ival = 0;
+
+ return ret;
+}
+
+static game_params *custom_params(config_item *cfg)
+{+ game_params *ret = snew(game_params);
+
+ ret->w = atoi(cfg[0].sval);
+ ret->h = atoi(cfg[1].sval);
+ ret->difficulty = cfg[2].ival;
+ ret->allowloops = cfg[3].ival;
+ ret->maxb = cfg[4].ival + 1;
+ ret->islands = (cfg[5].ival + 1) * 5;
+ ret->expansion = cfg[6].ival * 10;
+
+ return ret;
+}
+
+static char *validate_params(game_params *params, int full)
+{+ if (params->w < 3 || params->h < 3)
+ return "Width and height must be at least 3";
+ if (params->maxb < 1 || params->maxb > MAX_BRIDGES)
+ return "Too many bridges.";
+ if (full) {+ if (params->islands <= 0 || params->islands > 30)
+ return "%age of island squares must be between 1% and 30%";
+ if (params->expansion < 0 || params->expansion > 100)
+ return "Expansion factor must be between 0 and 100";
+ }
+ return NULL;
+}
+
+/* --- Game encoding and differences --- */
+
+static char *encode_game(game_state *state)
+{+ char *ret, *p;
+ int wh = state->w*state->h, run, x, y;
+ struct island *is;
+
+ ret = snewn(wh + 1, char);
+ p = ret;
+ run = 0;
+ for (y = 0; y < state->h; y++) {+ for (x = 0; x < state->w; x++) {+ is = INDEX(state, gridi, x, y);
+ if (is) {+ if (run) {+ *p++ = ('a'-1) + run;+ run = 0;
+ }
+ if (is->count < 10)
+ *p++ = '0' + is->count;
+ else
+ *p++ = 'A' + (is->count - 10);
+ } else {+ if (run == 26) {+ *p++ = ('a'-1) + run;+ run = 0;
+ }
+ run++;
+ }
+ }
+ }
+ if (run) {+ *p++ = ('a'-1) + run;+ run = 0;
+ }
+ *p = '\0';
+ assert(p - ret <= wh);
+
+ return ret;
+}
+
+static char *game_state_diff(game_state *src, game_state *dest)
+{+ int movesize = 256, movelen = 0;
+ char *move = snewn(movesize, char), buf[80];
+ int i, d, x, y, len;
+ grid_type gline, nline;
+ struct island *is_s, *is_d, *is_orth;
+
+#define APPEND do { \+ if (movelen + len >= movesize) { \+ movesize = movelen + len + 256; \
+ move = sresize(move, movesize, char); \
+ } \
+ strcpy(move + movelen, buf); \
+ movelen += len; \
+} while(0)
+
+ move[movelen++] = 'S';
+ move[movelen] = '\0';
+
+ assert(src->n_islands == dest->n_islands);
+
+ for (i = 0; i < src->n_islands; i++) {+ is_s = &src->islands[i];
+ is_d = &dest->islands[i];
+ assert(is_s->x == is_d->x);
+ assert(is_s->y == is_d->y);
+ assert(is_s->adj.npoints == is_d->adj.npoints); /* more paranoia */
+
+ for (d = 0; d < is_s->adj.npoints; d++) {+ if (is_s->adj.points[d].dx == -1 ||
+ is_s->adj.points[d].dy == -1) continue;
+
+ x = is_s->adj.points[d].x;
+ y = is_s->adj.points[d].y;
+ gline = is_s->adj.points[d].dx ? G_LINEH : G_LINEV;
+ nline = is_s->adj.points[d].dx ? G_NOLINEH : G_NOLINEV;
+ is_orth = INDEX(dest, gridi,
+ ISLAND_ORTHX(is_d, d), ISLAND_ORTHY(is_d, d));
+
+ if (GRIDCOUNT(src, x, y, gline) != GRIDCOUNT(dest, x, y, gline)) {+ assert(is_orth);
+ len = sprintf(buf, ";L%d,%d,%d,%d,%d",
+ is_s->x, is_s->y, is_orth->x, is_orth->y,
+ GRIDCOUNT(dest, x, y, gline));
+ APPEND;
+ }
+ if ((GRID(src,x,y) & nline) != (GRID(dest, x, y) & nline)) {+ assert(is_orth);
+ len = sprintf(buf, ";N%d,%d,%d,%d",
+ is_s->x, is_s->y, is_orth->x, is_orth->y);
+ APPEND;
+ }
+ }
+ if ((GRID(src, is_s->x, is_s->y) & G_MARK) !=
+ (GRID(dest, is_d->x, is_d->y) & G_MARK)) {+ len = sprintf(buf, ";M%d,%d", is_s->x, is_s->y);
+ APPEND;
+ }
+ }
+ return move;
+}
+
+/* --- Game setup and solving utilities --- */
+
+/* This function is optimised; a Quantify showed that lots of grid-generation time
+ * (>50%) was spent in here. Hence the IDX() stuff. */
+
+static void map_update_possibles(game_state *state)
+{+ int x, y, s, e, bl, i, np, maxb, w = state->w, idx;
+ struct island *is_s = NULL, *is_f = NULL;
+
+ /* Run down vertical stripes [un]setting possv... */
+ for (x = 0; x < state->w; x++) {+ idx = x;
+ s = e = -1;
+ bl = 0;
+ /* Unset possible flags until we find an island. */
+ for (y = 0; y < state->h; y++) {+ is_s = IDX(state, gridi, idx);
+ if (is_s) break;
+
+ IDX(state, possv, idx) = 0;
+ idx += w;
+ }
+ for (; y < state->h; y++) {+ is_f = IDX(state, gridi, idx);
+ if (is_f) {+ assert(is_s);
+ maxb = IDX(state, maxv, idx);
+ np = min(maxb, min(is_s->count, is_f->count));
+
+ if (s != -1) {+ for (i = s; i <= e; i++) {+ INDEX(state, possv, x, i) = bl ? 0 : np;
+ }
+ }
+ s = y+1;
+ bl = 0;
+ is_s = is_f;
+ } else {+ e = y;
+ if (IDX(state,grid,idx) & (G_LINEH|G_NOLINEV)) bl = 1;
+ }
+ idx += w;
+ }
+ if (s != -1) {+ for (i = s; i <= e; i++)
+ INDEX(state, possv, x, i) = 0;
+ }
+ }
+
+ /* ...and now do horizontal stripes [un]setting possh. */
+ /* can we lose this clone'n'hack? */
+ for (y = 0; y < state->h; y++) {+ idx = y*w;
+ s = e = -1;
+ bl = 0;
+ for (x = 0; x < state->w; x++) {+ is_s = IDX(state, gridi, idx);
+ if (is_s) break;
+
+ IDX(state, possh, idx) = 0;
+ idx += 1;
+ }
+ for (; x < state->w; x++) {+ is_f = IDX(state, gridi, idx);
+ if (is_f) {+ assert(is_s);
+ maxb = IDX(state, maxh, idx);
+ np = min(maxb, min(is_s->count, is_f->count));
+
+ if (s != -1) {+ for (i = s; i <= e; i++) {+ INDEX(state, possh, i, y) = bl ? 0 : np;
+ }
+ }
+ s = x+1;
+ bl = 0;
+ is_s = is_f;
+ } else {+ e = x;
+ if (IDX(state,grid,idx) & (G_LINEV|G_NOLINEH)) bl = 1;
+ }
+ idx += 1;
+ }
+ if (s != -1) {+ for (i = s; i <= e; i++)
+ INDEX(state, possh, i, y) = 0;
+ }
+ }
+}
+
+static void map_count(game_state *state)
+{+ int i, n, ax, ay;
+ grid_type flag, grid;
+ struct island *is;
+
+ for (i = 0; i < state->n_islands; i++) {+ is = &state->islands[i];
+ is->count = 0;
+ for (n = 0; n < is->adj.npoints; n++) {+ ax = is->adj.points[n].x;
+ ay = is->adj.points[n].y;
+ flag = (ax == is->x) ? G_LINEV : G_LINEH;
+ grid = GRID(state,ax,ay);
+ if (grid & flag) {+ is->count += INDEX(state,lines,ax,ay);
+ }
+ }
+ }
+}
+
+static void map_find_orthogonal(game_state *state)
+{+ int i;
+
+ for (i = 0; i < state->n_islands; i++) {+ island_find_orthogonal(&state->islands[i]);
+ }
+}
+
+static int grid_degree(game_state *state, int x, int y, int *nx_r, int *ny_r)
+{+ grid_type grid = SCRATCH(state, x, y), gline = grid & G_LINE;
+ struct island *is;
+ int x1, y1, x2, y2, c = 0, i, nx, ny;
+
+ nx = ny = -1; /* placate optimiser */
+ is = INDEX(state, gridi, x, y);
+ if (is) {+ for (i = 0; i < is->adj.npoints; i++) {+ gline = is->adj.points[i].dx ? G_LINEH : G_LINEV;
+ if (SCRATCH(state,
+ is->adj.points[i].x,
+ is->adj.points[i].y) & gline) {+ nx = is->adj.points[i].x;
+ ny = is->adj.points[i].y;
+ c++;
+ }
+ }
+ } else if (gline) {+ if (gline & G_LINEV) {+ x1 = x2 = x;
+ y1 = y-1; y2 = y+1;
+ } else {+ x1 = x-1; x2 = x+1;
+ y1 = y2 = y;
+ }
+ /* Non-island squares with edges in should never be pointing off the
+ * edge of the grid. */
+ assert(INGRID(state, x1, y1));
+ assert(INGRID(state, x2, y2));
+ if (SCRATCH(state, x1, y1) & (gline | G_ISLAND)) {+ nx = x1; ny = y1; c++;
+ }
+ if (SCRATCH(state, x2, y2) & (gline | G_ISLAND)) {+ nx = x2; ny = y2; c++;
+ }
+ }
+ if (c == 1) {+ assert(nx != -1 && ny != -1); /* paranoia */
+ *nx_r = nx; *ny_r = ny;
+ }
+ return c;
+}
+
+static int map_hasloops(game_state *state, int mark)
+{+ int x, y, ox, oy, nx, ny, loop = 0;
+
+ memcpy(state->scratch, state->grid, GRIDSZ(state));
+
+ /* This algorithm is actually broken; if there are two loops connected
+ * by bridges this will also highlight bridges. The correct algorithm
+ * uses a dsf and a two-pass edge-detection algorithm (see check_correct
+ * in slant.c); this is BALGE for now, especially since disallow-loops
+ * is not the default for this puzzle. If we want to fix this later then
+ * copy the alg in slant.c to the empty statement in map_group. */
+
+ /* Remove all 1-degree edges. */
+ for (y = 0; y < state->h; y++) {+ for (x = 0; x < state->w; x++) {+ ox = x; oy = y;
+ while (grid_degree(state, ox, oy, &nx, &ny) == 1) {+ /*debug(("hasloops: removing 1-degree at (%d,%d).\n", ox, oy));*/+ SCRATCH(state, ox, oy) &= ~(G_LINE|G_ISLAND);
+ ox = nx; oy = ny;
+ }
+ }
+ }
+ /* Mark any remaining edges as G_WARN, if required. */
+ for (x = 0; x < state->w; x++) {+ for (y = 0; y < state->h; y++) {+ if (GRID(state,x,y) & G_ISLAND) continue;
+
+ if (SCRATCH(state, x, y) & G_LINE) {+ if (mark) {+ /*debug(("hasloops: marking loop square at (%d,%d).\n",+ x, y));*/
+ GRID(state,x,y) |= G_WARN;
+ loop = 1;
+ } else
+ return 1; /* short-cut as soon as we find one */
+ } else {+ if (mark)
+ GRID(state,x,y) &= ~G_WARN;
+ }
+ }
+ }
+ return loop;
+}
+
+static void map_group(game_state *state)
+{+ int i, wh = state->w*state->h, d1, d2;
+ int x, y, x2, y2;
+ int *dsf = state->solver->dsf;
+ struct island *is, *is_join;
+
+ /* Initialise dsf. */
+ for (i = 0; i < wh; i++)
+ dsf[i] = i;
+
+ /* For each island, find connected islands right or down
+ * and merge the dsf for the island squares as well as the
+ * bridge squares. */
+ for (x = 0; x < state->w; x++) {+ for (y = 0; y < state->h; y++) {+ GRID(state,x,y) &= ~(G_SWEEP|G_WARN); /* for group_full. */
+
+ is = INDEX(state, gridi, x, y);
+ if (!is) continue;
+ d1 = DINDEX(x,y);
+ for (i = 0; i < is->adj.npoints; i++) {+ /* only want right/down */
+ if (is->adj.points[i].dx == -1 ||
+ is->adj.points[i].dy == -1) continue;
+
+ is_join = island_find_connection(is, i);
+ if (!is_join) continue;
+
+ d2 = DINDEX(is_join->x, is_join->y);
+ if (dsf_canonify(dsf,d1) == dsf_canonify(dsf,d2)) {+ ; /* we have a loop. See comment in map_hasloops. */
+ /* However, we still want to merge all squares joining
+ * this side-that-makes-a-loop. */
+ }
+ /* merge all squares between island 1 and island 2. */
+ for (x2 = x; x2 <= is_join->x; x2++) {+ for (y2 = y; y2 <= is_join->y; y2++) {+ d2 = DINDEX(x2,y2);
+ if (d1 != d2) dsf_merge(dsf,d1,d2);
+ }
+ }
+ }
+ }
+ }
+}
+
+static int map_group_check(game_state *state, int canon, int warn,
+ int *nislands_r)
+{+ int *dsf = state->solver->dsf, nislands = 0;
+ int x, y, i, allfull = 1;
+ struct island *is;
+
+ for (i = 0; i < state->n_islands; i++) {+ is = &state->islands[i];
+ if (dsf_canonify(dsf, DINDEX(is->x,is->y)) != canon) continue;
+
+ GRID(state, is->x, is->y) |= G_SWEEP;
+ nislands++;
+ if (island_countbridges(is) != is->count)
+ allfull = 0;
+ }
+ if (warn && allfull && nislands != state->n_islands) {+ /* we're full and this island group isn't the whole set.
+ * Mark all squares with this dsf canon as ERR. */
+ for (x = 0; x < state->w; x++) {+ for (y = 0; y < state->h; y++) {+ if (dsf_canonify(dsf, DINDEX(x,y)) == canon) {+ GRID(state,x,y) |= G_WARN;
+ }
+ }
+ }
+
+ }
+ if (nislands_r) *nislands_r = nislands;
+ return allfull;
+}
+
+static int map_group_full(game_state *state, int *ngroups_r)
+{+ int *dsf = state->solver->dsf, ngroups = 0;
+ int i, anyfull = 0;
+ struct island *is;
+
+ /* NB this assumes map_group (or sth else) has cleared G_SWEEP. */
+
+ for (i = 0; i < state->n_islands; i++) {+ is = &state->islands[i];
+ if (GRID(state,is->x,is->y) & G_SWEEP) continue;
+
+ ngroups++;
+ if (map_group_check(state, dsf_canonify(dsf, DINDEX(is->x,is->y)),
+ 1, NULL))
+ anyfull = 1;
+ }
+
+ *ngroups_r = ngroups;
+ return anyfull;
+}
+
+static int map_check(game_state *state)
+{+ int ngroups;
+
+ /* Check for loops, if necessary. */
+ if (!state->allowloops) {+ if (map_hasloops(state, 1))
+ return 0;
+ }
+
+ /* Place islands into island groups and check for early
+ * satisfied-groups. */
+ map_group(state); /* clears WARN and SWEEP */
+ if (map_group_full(state, &ngroups)) {+ if (ngroups == 1) return 1;
+ }
+ return 0;
+}
+
+static void map_clear(game_state *state)
+{+ int x, y;
+
+ for (x = 0; x < state->w; x++) {+ for (y = 0; y < state->h; y++) {+ /* clear most flags; might want to be slightly more careful here. */
+ GRID(state,x,y) &= G_ISLAND;
+ }
+ }
+}
+
+static void solve_join(struct island *is, int direction, int n, int is_max)
+{+ struct island *is_orth;
+ int d1, d2, *dsf = is->state->solver->dsf;
+ game_state *state = is->state; /* for DINDEX */
+
+ is_orth = INDEX(is->state, gridi,
+ ISLAND_ORTHX(is, direction),
+ ISLAND_ORTHY(is, direction));
+ assert(is_orth);
+ /*debug(("...joining (%d,%d) to (%d,%d) with %d bridge(s).\n",+ is->x, is->y, is_orth->x, is_orth->y, n));*/
+ island_join(is, is_orth, n, is_max);
+
+ if (n > 0 && !is_max) {+ d1 = DINDEX(is->x, is->y);
+ d2 = DINDEX(is_orth->x, is_orth->y);
+ if (dsf_canonify(dsf, d1) != dsf_canonify(dsf, d2))
+ dsf_merge(dsf, d1, d2);
+ }
+}
+
+static int solve_fillone(struct island *is)
+{+ int i, nadded = 0;
+
+ debug(("solve_fillone for island (%d,%d).\n", is->x, is->y));+
+ for (i = 0; i < is->adj.npoints; i++) {+ if (island_isadj(is, i)) {+ if (island_hasbridge(is, i)) {+ /* already attached; do nothing. */;
+ } else {+ solve_join(is, i, 1, 0);
+ nadded++;
+ }
+ }
+ }
+ return nadded;
+}
+
+static int solve_fill(struct island *is)
+{+ /* for each unmarked adjacent, make sure we convert every possible bridge
+ * to a real one, and then work out the possibles afresh. */
+ int i, nnew, ncurr, nadded = 0, missing;
+
+ debug(("solve_fill for island (%d,%d).\n", is->x, is->y));+
+ missing = is->count - island_countbridges(is);
+ if (missing < 0) return 0;
+
+ /* very like island_countspaces. */
+ for (i = 0; i < is->adj.npoints; i++) {+ nnew = island_adjspace(is, 1, missing, i);
+ if (nnew) {+ ncurr = GRIDCOUNT(is->state,
+ is->adj.points[i].x, is->adj.points[i].y,
+ is->adj.points[i].dx ? G_LINEH : G_LINEV);
+
+ solve_join(is, i, nnew + ncurr, 0);
+ nadded += nnew;
+ }
+ }
+ return nadded;
+}
+
+static int solve_island_stage1(struct island *is, int *didsth_r)
+{+ int bridges = island_countbridges(is);
+ int nspaces = island_countspaces(is, 1);
+ int nadj = island_countadj(is);
+ int didsth = 0;
+
+ assert(didsth_r);
+
+ /*debug(("island at (%d,%d) filled %d/%d (%d spc) nadj %d\n",+ is->x, is->y, bridges, is->count, nspaces, nadj));*/
+ if (bridges > is->count) {+ /* We only ever add bridges when we're sure they fit, or that's
+ * the only place they can go. If we've added bridges such that
+ * another island has become wrong, the puzzle must not have had
+ * a solution. */
+ debug(("...island at (%d,%d) is overpopulated!\n", is->x, is->y));+ return 0;
+ } else if (bridges == is->count) {+ /* This island is full. Make sure it's marked (and update
+ * possibles if we did). */
+ if (!(GRID(is->state, is->x, is->y) & G_MARK)) {+ debug(("...marking island (%d,%d) as full.\n", is->x, is->y));+ island_togglemark(is);
+ didsth = 1;
+ }
+ } else if (GRID(is->state, is->x, is->y) & G_MARK) {+ debug(("...island (%d,%d) is marked but unfinished!\n",+ is->x, is->y));
+ return 0; /* island has been marked unfinished; no solution from here. */
+ } else {+ /* This is the interesting bit; we try and fill in more information
+ * about this island. */
+ if (is->count == bridges + nspaces) {+ if (solve_fill(is) > 0) didsth = 1;
+ } else if (is->count > ((nadj-1) * is->state->maxb)) {+ /* must have at least one bridge in each possible direction. */
+ if (solve_fillone(is) > 0) didsth = 1;
+ }
+ }
+ if (didsth) {+ map_update_possibles(is->state);
+ *didsth_r = 1;
+ }
+ return 1;
+}
+
+/* returns non-zero if a new line here would cause a loop. */
+static int solve_island_checkloop(struct island *is, int direction)
+{+ struct island *is_orth;
+ int *dsf = is->state->solver->dsf, d1, d2;
+ game_state *state = is->state;
+
+ if (is->state->allowloops) return 0; /* don't care anyway */
+ if (island_hasbridge(is, direction)) return 0; /* already has a bridge */
+ if (island_isadj(is, direction) == 0) return 0; /* no adj island */
+
+ is_orth = INDEX(is->state, gridi,
+ ISLAND_ORTHX(is,direction),
+ ISLAND_ORTHY(is,direction));
+ if (!is_orth) return 0;
+
+ d1 = DINDEX(is->x, is->y);
+ d2 = DINDEX(is_orth->x, is_orth->y);
+ if (dsf_canonify(dsf, d1) == dsf_canonify(dsf, d2)) {+ /* two islands are connected already; don't join them. */
+ return 1;
+ }
+ return 0;
+}
+
+static int solve_island_stage2(struct island *is, int *didsth_r)
+{+ int added = 0, removed = 0, navail = 0, nadj, i;
+
+ assert(didsth_r);
+
+ for (i = 0; i < is->adj.npoints; i++) {+ if (solve_island_checkloop(is, i)) {+ debug(("removing possible loop at (%d,%d) direction %d.\n",+ is->x, is->y, i));
+ solve_join(is, i, -1, 0);
+ map_update_possibles(is->state);
+ removed = 1;
+ } else {+ navail += island_isadj(is, i);
+ /*debug(("stage2: navail for (%d,%d) direction (%d,%d) is %d.\n",+ is->x, is->y,
+ is->adj.points[i].dx, is->adj.points[i].dy,
+ island_isadj(is, i)));*/
+ }
+ }
+
+ /*debug(("island at (%d,%d) navail %d: checking...\n", is->x, is->y, navail));*/+
+ for (i = 0; i < is->adj.npoints; i++) {+ if (!island_hasbridge(is, i)) {+ nadj = island_isadj(is, i);
+ if (nadj > 0 && (navail - nadj) < is->count) {+ /* we couldn't now complete the island without at
+ * least one bridge here; put it in. */
+ /*debug(("nadj %d, navail %d, is->count %d.\n",+ nadj, navail, is->count));*/
+ debug(("island at (%d,%d) direction (%d,%d) must have 1 bridge\n",+ is->x, is->y,
+ is->adj.points[i].dx, is->adj.points[i].dy));
+ solve_join(is, i, 1, 0);
+ added = 1;
+ /*debug_state(is->state);
+ debug_possibles(is->state);*/
+ }
+ }
+ }
+ if (added) map_update_possibles(is->state);
+ if (added || removed) *didsth_r = 1;
+ return 1;
+}
+
+static int solve_island_subgroup(struct island *is, int direction, int n)
+{+ struct island *is_join;
+ int nislands, *dsf = is->state->solver->dsf;
+ game_state *state = is->state;
+
+ debug(("..checking subgroups.\n"));+
+ /* if is isn't full, return 0. */
+ if (n < is->count) {+ debug(("...orig island (%d,%d) not full.\n", is->x, is->y));+ return 0;
+ }
+
+ is_join = INDEX(state, gridi,
+ ISLAND_ORTHX(is, direction),
+ ISLAND_ORTHY(is, direction));
+ assert(is_join);
+
+ /* if is_join isn't full, return 0. */
+ if (island_countbridges(is_join) < is_join->count) {+ debug(("...dest island (%d,%d) not full.\n", is_join->x, is_join->y));+ return 0;
+ }
+
+ /* Check group membership for is->dsf; if it's full return 1. */
+ if (map_group_check(state, dsf_canonify(dsf, DINDEX(is->x,is->y)),
+ 0, &nislands)) {+ if (nislands < state->n_islands) {+ /* we have a full subgroup that isn't the whole set.
+ * This isn't allowed. */
+ debug(("island at (%d,%d) makes full subgroup, disallowing.\n",+ is->x, is->y, n));
+ return 1;
+ } else {+ debug(("...has finished puzzle.\n"));+ }
+ }
+ return 0;
+}
+
+static int solve_island_impossible(game_state *state)
+{+ struct island *is;
+ int i;
+
+ /* If any islands are impossible, return 1. */
+ for (i = 0; i < state->n_islands; i++) {+ is = &state->islands[i];
+ if (island_impossible(is, 0)) {+ debug(("island at (%d,%d) has become impossible, disallowing.\n",+ is->x, is->y));
+ return 1;
+ }
+ }
+ return 0;
+}
+
+/* Bear in mind that this function is really rather inefficient. */
+static int solve_island_stage3(struct island *is, int *didsth_r)
+{+ int i, n, x, y, missing, spc, curr, maxb, didsth = 0;
+ int wh = is->state->w * is->state->h;
+ struct solver_state *ss = is->state->solver;
+
+ assert(didsth_r);
+
+ missing = is->count - island_countbridges(is);
+ if (missing <= 0) return 1;
+
+ for (i = 0; i < is->adj.npoints; i++) {+ /* We only do right- or down-pointing bridges. */
+ if (is->adj.points[i].dx == -1 ||
+ is->adj.points[i].dy == -1) continue;
+
+ x = is->adj.points[i].x;
+ y = is->adj.points[i].y;
+ spc = island_adjspace(is, 1, missing, i);
+ if (spc == 0) continue;
+
+ curr = GRIDCOUNT(is->state, x, y,
+ is->adj.points[i].dx ? G_LINEH : G_LINEV);
+ debug(("island at (%d,%d) s3, trying %d - %d bridges.\n",+ is->x, is->y, curr+1, curr+spc));
+
+ /* Now we know that this island could have more bridges,
+ * to bring the total from curr+1 to curr+spc. */
+ maxb = -1;
+ /* We have to squirrel the dsf away and restore it afterwards;
+ * it is additive only, and can't be removed from. */
+ memcpy(ss->tmpdsf, ss->dsf, wh*sizeof(int));
+ for (n = curr+1; n <= curr+spc; n++) {+ solve_join(is, i, n, 0);
+ map_update_possibles(is->state);
+
+ if (solve_island_subgroup(is, i, n) ||
+ solve_island_impossible(is->state)) {+ maxb = n-1;
+ debug(("island at (%d,%d) d(%d,%d) new max of %d bridges:\n",+ is->x, is->y,
+ is->adj.points[i].dx, is->adj.points[i].dy,
+ maxb));
+ break;
+ }
+ }
+ solve_join(is, i, curr, 0); /* put back to before. */
+ memcpy(ss->dsf, ss->tmpdsf, wh*sizeof(int));
+
+ if (maxb != -1) {+ /*debug_state(is->state);*/
+ if (maxb == 0) {+ debug(("...adding NOLINE.\n"));+ solve_join(is, i, -1, 0); /* we can't have any bridges here. */
+ didsth = 1;
+ } else {+ debug(("...setting maximum\n"));+ solve_join(is, i, maxb, 1);
+ }
+ }
+ map_update_possibles(is->state);
+ }
+ if (didsth) *didsth_r = didsth;
+ return 1;
+}
+
+#define CONTINUE_IF_FULL do { \+if (GRID(state, is->x, is->y) & G_MARK) { \+ /* island full, don't try fixing it */ \
+ continue; \
+} } while(0)
+
+static int solve_sub(game_state *state, int difficulty, int depth)
+{+ struct island *is;
+ int i, didsth;
+
+ while (1) {+ didsth = 0;
+
+ /* First island iteration: things we can work out by looking at
+ * properties of the island as a whole. */
+ for (i = 0; i < state->n_islands; i++) {+ is = &state->islands[i];
+ if (!solve_island_stage1(is, &didsth)) return 0;
+ }
+ if (didsth) continue;
+ else if (difficulty < 1) break;
+
+ /* Second island iteration: thing we can work out by looking at
+ * properties of individual island connections. */
+ for (i = 0; i < state->n_islands; i++) {+ is = &state->islands[i];
+ CONTINUE_IF_FULL;
+ if (!solve_island_stage2(is, &didsth)) return 0;
+ }
+ if (didsth) continue;
+ else if (difficulty < 2) break;
+
+ /* Third island iteration: things we can only work out by looking
+ * at groups of islands. */
+ for (i = 0; i < state->n_islands; i++) {+ is = &state->islands[i];
+ if (!solve_island_stage3(is, &didsth)) return 0;
+ }
+ if (didsth) continue;
+ else if (difficulty < 3) break;
+
+ /* If we can be bothered, write a recursive solver to finish here. */
+ break;
+ }
+ if (map_check(state)) return 1; /* solved it */
+ return 0;
+}
+
+static void solve_for_hint(game_state *state)
+{+ map_group(state);
+ solve_sub(state, 10, 0);
+}
+
+static int solve_from_scratch(game_state *state, int difficulty)
+{+ map_clear(state);
+ map_group(state);
+ map_update_possibles(state);
+ return solve_sub(state, difficulty, 0);
+}
+
+/* --- New game functions --- */
+
+static game_state *new_state(game_params *params)
+{+ game_state *ret = snew(game_state);
+ int wh = params->w * params->h, i;
+
+ ret->w = params->w;
+ ret->h = params->h;
+ ret->allowloops = params->allowloops;
+ ret->maxb = params->maxb;
+ ret->params = *params;
+
+ ret->grid = snewn(wh, grid_type);
+ memset(ret->grid, 0, GRIDSZ(ret));
+ ret->scratch = snewn(wh, grid_type);
+ memset(ret->scratch, 0, GRIDSZ(ret));
+
+ ret->wha = snewn(wh*N_WH_ARRAYS, char);
+ memset(ret->wha, 0, wh*N_WH_ARRAYS*sizeof(char));
+
+ ret->possv = ret->wha;
+ ret->possh = ret->wha + wh;
+ ret->lines = ret->wha + wh*2;
+ ret->maxv = ret->wha + wh*3;
+ ret->maxh = ret->wha + wh*4;
+
+ memset(ret->maxv, ret->maxb, wh*sizeof(char));
+ memset(ret->maxh, ret->maxb, wh*sizeof(char));
+
+ ret->islands = NULL;
+ ret->n_islands = 0;
+ ret->n_islands_alloc = 0;
+
+ ret->gridi = snewn(wh, struct island *);
+ for (i = 0; i < wh; i++) ret->gridi[i] = NULL;
+
+ ret->solved = ret->completed = 0;
+
+ ret->solver = snew(struct solver_state);
+ ret->solver->dsf = snewn(wh, int);
+ ret->solver->tmpdsf = snewn(wh, int);
+ for (i = 0; i < wh; i++) ret->solver->dsf[i] = i;
+
+ ret->solver->refcount = 1;
+
+ return ret;
+}
+
+static game_state *dup_game(game_state *state)
+{+ game_state *ret = snew(game_state);
+ int wh = state->w*state->h;
+
+ ret->w = state->w;
+ ret->h = state->h;
+ ret->allowloops = state->allowloops;
+ ret->maxb = state->maxb;
+ ret->params = state->params;
+
+ ret->grid = snewn(wh, grid_type);
+ memcpy(ret->grid, state->grid, GRIDSZ(ret));
+ ret->scratch = snewn(wh, grid_type);
+ memcpy(ret->scratch, state->scratch, GRIDSZ(ret));
+
+ ret->wha = snewn(wh*N_WH_ARRAYS, char);
+ memcpy(ret->wha, state->wha, wh*N_WH_ARRAYS*sizeof(char));
+
+ ret->possv = ret->wha;
+ ret->possh = ret->wha + wh;
+ ret->lines = ret->wha + wh*2;
+ ret->maxv = ret->wha + wh*3;
+ ret->maxh = ret->wha + wh*4;
+
+ ret->islands = snewn(state->n_islands, struct island);
+ memcpy(ret->islands, state->islands, state->n_islands * sizeof(struct island));
+ ret->n_islands = ret->n_islands_alloc = state->n_islands;
+
+ ret->gridi = snewn(wh, struct island *);
+ fixup_islands_for_realloc(ret);
+
+ ret->solved = state->solved;
+ ret->completed = state->completed;
+
+ ret->solver = state->solver;
+ ret->solver->refcount++;
+
+ return ret;
+}
+
+static void free_game(game_state *state)
+{+ if (--state->solver->refcount <= 0) {+ sfree(state->solver->dsf);
+ sfree(state->solver->tmpdsf);
+ sfree(state->solver);
+ }
+
+ sfree(state->islands);
+ sfree(state->gridi);
+
+ sfree(state->wha);
+
+ sfree(state->scratch);
+ sfree(state->grid);
+ sfree(state);
+}
+
+#define MAX_NEWISLAND_TRIES 50
+
+#define ORDER(a,b) do { if (a < b) { int tmp=a; int a=b; int b=tmp; } } while(0)+
+static char *new_game_desc(game_params *params, random_state *rs,
+ char **aux, int interactive)
+{+ game_state *tobuild = NULL;
+ int i, j, wh = params->w * params->h, x, y, dx, dy;
+ int minx, miny, maxx, maxy, joinx, joiny, newx, newy, diffx, diffy;
+ int ni_req = max((params->islands * wh) / 100, 2), ni_curr, ni_bad;
+ struct island *is, *is2;
+ char *ret;
+ unsigned int echeck;
+
+ /* pick a first island position randomly. */
+generate:
+ if (tobuild) free_game(tobuild);
+ tobuild = new_state(params);
+
+ x = random_upto(rs, params->w);
+ y = random_upto(rs, params->h);
+ island_add(tobuild, x, y, 0);
+ ni_curr = 1;
+ ni_bad = 0;
+ debug(("Created initial island at (%d,%d).\n", x, y));+
+ while (ni_curr < ni_req) {+ /* Pick a random island to try and extend from. */
+ i = random_upto(rs, tobuild->n_islands);
+ is = &tobuild->islands[i];
+
+ /* Pick a random direction to extend in. */
+ j = random_upto(rs, is->adj.npoints);
+ dx = is->adj.points[j].x - is->x;
+ dy = is->adj.points[j].y - is->y;
+
+ /* Find out limits of where we could put a new island. */
+ joinx = joiny = -1;
+ minx = is->x + 2*dx; miny = is->y + 2*dy; /* closest is 2 units away. */
+ x = is->x+dx; y = is->y+dy;
+ if (GRID(tobuild,x,y) & (G_LINEV|G_LINEH)) {+ /* already a line next to the island, continue. */
+ goto bad;
+ }
+ while (1) {+ if (x < 0 || x >= params->w || y < 0 || y >= params->h) {+ /* got past the edge; put a possible at the island
+ * and exit. */
+ maxx = x-dx; maxy = y-dy;
+ goto foundmax;
+ }
+ if (GRID(tobuild,x,y) & G_ISLAND) {+ /* could join up to an existing island... */
+ joinx = x; joiny = y;
+ /* ... or make a new one 2 spaces away. */
+ maxx = x - 2*dx; maxy = y - 2*dy;
+ goto foundmax;
+ } else if (GRID(tobuild,x,y) & (G_LINEV|G_LINEH)) {+ /* could make a new one 1 space away from the line. */
+ maxx = x - dx; maxy = y - dy;
+ goto foundmax;
+ }
+ x += dx; y += dy;
+ }
+
+foundmax:
+ debug(("Island at (%d,%d) with d(%d,%d) has new positions "+ "(%d,%d) -> (%d,%d), join (%d,%d).\n",
+ is->x, is->y, dx, dy, minx, miny, maxx, maxy, joinx, joiny));
+ /* Now we know where we could either put a new island
+ * (between min and max), or (if loops are allowed) could join on
+ * to an existing island (at join). */
+ if (params->allowloops && joinx != -1 && joiny != -1) {+ if (random_upto(rs, 100) < (unsigned long)params->expansion) {+ is2 = INDEX(tobuild, gridi, joinx, joiny);
+ debug(("Joining island at (%d,%d) to (%d,%d).\n",+ is->x, is->y, is2->x, is2->y));
+ goto join;
+ }
+ }
+ diffx = (maxx - minx) * dx;
+ diffy = (maxy - miny) * dy;
+ if (diffx < 0 || diffy < 0) goto bad;
+ if (random_upto(rs,100) < (unsigned long)params->expansion) {+ newx = maxx; newy = maxy;
+ debug(("Creating new island at (%d,%d) (expanded).\n", newx, newy));+ } else {+ newx = minx + random_upto(rs,diffx+1)*dx;
+ newy = miny + random_upto(rs,diffy+1)*dy;
+ debug(("Creating new island at (%d,%d).\n", newx, newy));+ }
+ /* check we're not next to island in the other orthogonal direction. */
+ if ((INGRID(tobuild,newx+dy,newy+dx) && (GRID(tobuild,newx+dy,newy+dx) & G_ISLAND)) ||
+ (INGRID(tobuild,newx-dy,newy-dx) && (GRID(tobuild,newx-dy,newy-dx) & G_ISLAND))) {+ debug(("New location is adjacent to island, skipping.\n"));+ goto bad;
+ }
+ is2 = island_add(tobuild, newx, newy, 0);
+ /* Must get is again at this point; the array might have
+ * been realloced by island_add... */
+ is = &tobuild->islands[i]; /* ...but order will not change. */
+
+ ni_curr++; ni_bad = 0;
+join:
+ island_join(is, is2, random_upto(rs, tobuild->maxb)+1, 0);
+ debug_state(tobuild);
+ continue;
+
+bad:
+ ni_bad++;
+ if (ni_bad > MAX_NEWISLAND_TRIES) {+ debug(("Unable to create any new islands after %d tries; "+ "created %d [%d%%] (instead of %d [%d%%] requested).\n",
+ MAX_NEWISLAND_TRIES,
+ ni_curr, ni_curr * 100 / wh,
+ ni_req, ni_req * 100 / wh));
+ goto generated;
+ }
+ }
+
+generated:
+ if (ni_curr == 1) {+ debug(("Only generated one island (!), retrying.\n"));+ goto generate;
+ }
+ /* Check we have at least one island on each extremity of the grid. */
+ echeck = 0;
+ for (x = 0; x < params->w; x++) {+ if (INDEX(tobuild, gridi, x, 0)) echeck |= 1;
+ if (INDEX(tobuild, gridi, x, params->w-1)) echeck |= 2;
+ }
+ for (y = 0; y < params->h; y++) {+ if (INDEX(tobuild, gridi, 0, y)) echeck |= 4;
+ if (INDEX(tobuild, gridi, params->h-1, y)) echeck |= 8;
+ }
+ if (echeck != 15) {+ debug(("Generated grid doesn't fill to sides, retrying.\n"));+ goto generate;
+ }
+
+ map_count(tobuild);
+ map_find_orthogonal(tobuild);
+
+ if (params->difficulty > 0) {+ if (solve_from_scratch(tobuild, params->difficulty-1) > 0) {+ debug(("Grid is solvable at difficulty %d (too easy); retrying.\n",+ params->difficulty-1));
+ goto generate;
+ }
+ }
+
+ if (solve_from_scratch(tobuild, params->difficulty) == 0) {+ debug(("Grid not solvable at difficulty %d, (too hard); retrying.\n",+ params->difficulty));
+ goto generate;
+ }
+
+ /* ... tobuild is now solved. We rely on this making the diff for aux. */
+ debug_state(tobuild);
+ ret = encode_game(tobuild);
+ {+ game_state *clean = dup_game(tobuild);
+ map_clear(clean);
+ map_update_possibles(clean);
+ *aux = game_state_diff(clean, tobuild);
+ free_game(clean);
+ }
+ free_game(tobuild);
+
+ return ret;
+}
+
+static char *validate_desc(game_params *params, char *desc)
+{+ int i, wh = params->w * params->h;
+
+ for (i = 0; i < wh; i++) {+ if (*desc >= '1' && *desc <= '9')
+ /* OK */;
+ else if (*desc >= 'a' && *desc <= 'z')
+ i += *desc - 'a'; /* plus the i++ */
+ else if (*desc >= 'A' && *desc <= 'G')
+ /* OK */;
+ else if (*desc == 'V' || *desc == 'W' ||
+ *desc == 'X' || *desc == 'Y' ||
+ *desc == 'H' || *desc == 'I' ||
+ *desc == 'J' || *desc == 'K')
+ /* OK */;
+ else if (!*desc)
+ return "Game description shorter than expected";
+ else
+ return "Game description containers unexpected character";
+ desc++;
+ }
+ if (*desc || i > wh)
+ return "Game description longer than expected";
+
+ return NULL;
+}
+
+static game_state *new_game_sub(game_params *params, char *desc)
+{+ game_state *state = new_state(params);
+ int x, y, run = 0;
+
+ debug(("new_game[_sub]: desc = '%s'.\n", desc));+
+ for (y = 0; y < params->h; y++) {+ for (x = 0; x < params->w; x++) {+ char c = '\0';
+
+ if (run == 0) {+ c = *desc++;
+ assert(c != 'S');
+ if (c >= 'a' && c <= 'z')
+ run = c - 'a' + 1;
+ }
+
+ if (run > 0) {+ c = 'S';
+ run--;
+ }
+
+ switch (c) {+ case '1': case '2': case '3': case '4':
+ case '5': case '6': case '7': case '8': case '9':
+ island_add(state, x, y, (c - '0'));
+ break;
+
+ case 'A': case 'B': case 'C': case 'D':
+ case 'E': case 'F': case 'G':
+ island_add(state, x, y, (c - 'A') + 10);
+ break;
+
+ case 'S':
+ /* empty square */
+ break;
+
+ default:
+ assert(!"Malformed desc.");
+ break;
+ }
+ }
+ }
+ if (*desc) assert(!"Over-long desc.");
+
+ map_find_orthogonal(state);
+ map_update_possibles(state);
+
+ return state;
+}
+
+static game_state *new_game(midend *me, game_params *params, char *desc)
+{+ return new_game_sub(params, desc);
+}
+
+struct game_ui {+ int dragx_src, dragy_src; /* source; -1 means no drag */
+ int dragx_dst, dragy_dst; /* src's closest orth island. */
+ grid_type todraw;
+ int dragging, drag_is_noline, nlines;
+};
+
+static char *ui_cancel_drag(game_ui *ui)
+{+ ui->dragx_src = ui->dragy_src = -1;
+ ui->dragx_dst = ui->dragy_dst = -1;
+ ui->dragging = 0;
+ return "";
+}
+
+static game_ui *new_ui(game_state *state)
+{+ game_ui *ui = snew(game_ui);
+ ui_cancel_drag(ui);
+ return ui;
+}
+
+static void free_ui(game_ui *ui)
+{+ sfree(ui);
+}
+
+static char *encode_ui(game_ui *ui)
+{+ return NULL;
+}
+
+static void decode_ui(game_ui *ui, char *encoding)
+{+}
+
+static void game_changed_state(game_ui *ui, game_state *oldstate,
+ game_state *newstate)
+{+}
+
+struct game_drawstate {+ int tilesize;
+ int w, h;
+ grid_type *grid;
+ int *lv, *lh;
+ int started, dragging;
+};
+
+static char *update_drag_dst(game_state *state, game_ui *ui, game_drawstate *ds,
+ int nx, int ny)
+{+ int ox, oy, dx, dy, i, currl, maxb;
+ struct island *is;
+ grid_type gtype, ntype, mtype, curr;
+
+ if (ui->dragx_src == -1 || ui->dragy_src == -1) return NULL;
+
+ ui->dragx_dst = -1;
+ ui->dragy_dst = -1;
+
+ /* work out which of the four directions we're closest to... */
+ ox = COORD(ui->dragx_src) + TILE_SIZE/2;
+ oy = COORD(ui->dragy_src) + TILE_SIZE/2;
+
+ if (abs(nx-ox) < abs(ny-oy)) {+ dx = 0;
+ dy = (ny-oy) < 0 ? -1 : 1;
+ gtype = G_LINEV; ntype = G_NOLINEV; mtype = G_MARKV;
+ maxb = INDEX(state, maxv, ui->dragx_src+dx, ui->dragy_src+dy);
+ } else {+ dy = 0;
+ dx = (nx-ox) < 0 ? -1 : 1;
+ gtype = G_LINEH; ntype = G_NOLINEH; mtype = G_MARKH;
+ maxb = INDEX(state, maxh, ui->dragx_src+dx, ui->dragy_src+dy);
+ }
+ if (ui->drag_is_noline) {+ ui->todraw = ntype;
+ } else {+ curr = GRID(state, ui->dragx_src+dx, ui->dragy_src+dy);
+ currl = INDEX(state, lines, ui->dragx_src+dx, ui->dragy_src+dy);
+
+ if (curr & gtype) {+ if (currl == maxb) {+ ui->todraw = 0;
+ ui->nlines = 0;
+ } else {+ ui->todraw = gtype;
+ ui->nlines = currl + 1;
+ }
+ } else {+ ui->todraw = gtype;
+ ui->nlines = 1;
+ }
+ }
+
+ /* ... and see if there's an island off in that direction. */
+ is = INDEX(state, gridi, ui->dragx_src, ui->dragy_src);
+ for (i = 0; i < is->adj.npoints; i++) {+ if (is->adj.points[i].off == 0) continue;
+ curr = GRID(state, is->x+dx, is->y+dy);
+ if (curr & mtype) continue; /* don't allow changes to marked lines. */
+ if (ui->drag_is_noline) {+ if (curr & gtype) continue; /* no no-line where already a line */
+ } else {+ if (POSSIBLES(state, dx, is->x+dx, is->y+dy) == 0) continue; /* no line if !possible. */
+ if (curr & ntype) continue; /* can't have a bridge where there's a no-line. */
+ }
+
+ if (is->adj.points[i].dx == dx &&
+ is->adj.points[i].dy == dy) {+ ui->dragx_dst = ISLAND_ORTHX(is,i);
+ ui->dragy_dst = ISLAND_ORTHY(is,i);
+ }
+ }
+ /*debug(("update_drag src (%d,%d) d(%d,%d) dst (%d,%d)\n",+ ui->dragx_src, ui->dragy_src, dx, dy,
+ ui->dragx_dst, ui->dragy_dst));*/
+ return "";
+}
+
+static char *finish_drag(game_state *state, game_ui *ui)
+{+ char buf[80];
+
+ if (ui->dragx_src == -1 || ui->dragy_src == -1)
+ return NULL;
+ if (ui->dragx_dst == -1 || ui->dragy_dst == -1)
+ return ui_cancel_drag(ui);
+
+ if (ui->drag_is_noline) {+ sprintf(buf, "N%d,%d,%d,%d",
+ ui->dragx_src, ui->dragy_src,
+ ui->dragx_dst, ui->dragy_dst);
+ } else {+ sprintf(buf, "L%d,%d,%d,%d,%d",
+ ui->dragx_src, ui->dragy_src,
+ ui->dragx_dst, ui->dragy_dst, ui->nlines);
+ }
+
+ ui_cancel_drag(ui);
+
+ return dupstr(buf);
+}
+
+static char *interpret_move(game_state *state, game_ui *ui, game_drawstate *ds,
+ int x, int y, int button)
+{+ int gx = FROMCOORD(x), gy = FROMCOORD(y);
+ char buf[80], *ret;
+ grid_type ggrid = INGRID(state,gx,gy) ? GRID(state,gx,gy) : 0;
+
+ if (button == LEFT_BUTTON || button == RIGHT_BUTTON) {+ if (!INGRID(state, gx, gy)) return NULL;
+ if ((ggrid & G_ISLAND) && !(ggrid & G_MARK)) {+ ui->dragx_src = gx;
+ ui->dragy_src = gy;
+ return "";
+ } else
+ return ui_cancel_drag(ui);
+ } else if (button == LEFT_DRAG || button == RIGHT_DRAG) {+ if (gx != ui->dragx_src || gy != ui->dragy_src) {+ ui->dragging = 1;
+ ui->drag_is_noline = (button == RIGHT_DRAG) ? 1 : 0;
+ return update_drag_dst(state, ui, ds, x, y);
+ } else {+ /* cancel a drag when we go back to the starting point */
+ ui->dragx_dst = -1;
+ ui->dragy_dst = -1;
+ return "";
+ }
+ } else if (button == LEFT_RELEASE || button == RIGHT_RELEASE) {+ if (ui->dragging) {+ return finish_drag(state, ui);
+ } else {+ ui_cancel_drag(ui);
+ if (!INGRID(state, gx, gy)) return NULL;
+ if (!(GRID(state, gx, gy) & G_ISLAND)) return NULL;
+ sprintf(buf, "M%d,%d", gx, gy);
+ return dupstr(buf);
+ }
+ } else if (button == 'h' || button == 'H') {+ game_state *solved = dup_game(state);
+ solve_for_hint(solved);
+ ret = game_state_diff(state, solved);
+ free_game(solved);
+ return ret;
+ }
+
+ return NULL;
+}
+
+static game_state *execute_move(game_state *state, char *move)
+{+ game_state *ret = dup_game(state);
+ int x1, y1, x2, y2, nl, n;
+ struct island *is1, *is2;
+ char c;
+
+ debug(("execute_move: %s\n", move));+
+ if (!*move) goto badmove;
+ while (*move) {+ c = *move++;
+ if (c == 'S') {+ ret->solved = TRUE;
+ n = 0;
+ } else if (c == 'L') {+ if (sscanf(move, "%d,%d,%d,%d,%d%n",
+ &x1, &y1, &x2, &y2, &nl, &n) != 5)
+ goto badmove;
+ is1 = INDEX(ret, gridi, x1, y1);
+ is2 = INDEX(ret, gridi, x2, y2);
+ if (!is1 || !is2) goto badmove;
+ if (nl < 0 || nl > state->maxb) goto badmove;
+ island_join(is1, is2, nl, 0);
+ } else if (c == 'N') {+ if (sscanf(move, "%d,%d,%d,%d%n",
+ &x1, &y1, &x2, &y2, &n) != 4)
+ goto badmove;
+ is1 = INDEX(ret, gridi, x1, y1);
+ is2 = INDEX(ret, gridi, x2, y2);
+ if (!is1 || !is2) goto badmove;
+ island_join(is1, is2, -1, 0);
+ } else if (c == 'M') {+ if (sscanf(move, "%d,%d%n",
+ &x1, &y1, &n) != 2)
+ goto badmove;
+ is1 = INDEX(ret, gridi, x1, y1);
+ if (!is1) goto badmove;
+ island_togglemark(is1);
+ } else
+ goto badmove;
+
+ move += n;
+ if (*move == ';')
+ move++;
+ else if (*move) goto badmove;
+ }
+
+ map_update_possibles(ret);
+ if (map_check(ret)) {+ debug(("Game completed.\n"));+ ret->completed = 1;
+ }
+ return ret;
+
+badmove:
+ debug(("%s: unrecognised move.\n", move));+ free_game(ret);
+ return NULL;
+}
+
+static char *solve_game(game_state *state, game_state *currstate,
+ char *aux, char **error)
+{+ char *ret;
+ game_state *solved;
+
+ if (aux) {+ debug(("solve_game: aux = %s\n", aux));+ solved = execute_move(state, aux);
+ if (!solved) {+ *error = "Generated aux string is not a valid move (!).";
+ return NULL;
+ }
+ } else {+ solved = dup_game(state);
+ /* solve with max strength... */
+ if (solve_from_scratch(solved, 10) == 0) {+ free_game(solved);
+ *error = "Game does not have a (non-recursive) solution.";
+ return NULL;
+ }
+ }
+ ret = game_state_diff(currstate, solved);
+ free_game(solved);
+ debug(("solve_game: ret = %s\n", ret));+ return ret;
+}
+
+/* ----------------------------------------------------------------------
+ * Drawing routines.
+ */
+
+static void game_compute_size(game_params *params, int tilesize,
+ int *x, int *y)
+{+ /* Ick: fake up `ds->tilesize' for macro expansion purposes */
+ struct { int tilesize; } ads, *ds = &ads;+ ads.tilesize = tilesize;
+
+ *x = TILE_SIZE * params->w + 2 * BORDER;
+ *y = TILE_SIZE * params->h + 2 * BORDER;
+}
+
+static void game_set_size(drawing *dr, game_drawstate *ds,
+ game_params *params, int tilesize)
+{+ ds->tilesize = tilesize;
+}
+
+static float *game_colours(frontend *fe, game_state *state, int *ncolours)
+{+ float *ret = snewn(3 * NCOLOURS, float);
+ int i;
+
+ game_mkhighlight(fe, ret, COL_BACKGROUND, COL_HIGHLIGHT, COL_LOWLIGHT);
+
+ for (i = 0; i < 3; i++) {+ ret[COL_FOREGROUND * 3 + i] = 0.0F;
+ ret[COL_HINT * 3 + i] = ret[COL_LOWLIGHT * 3 + i];
+ ret[COL_GRID * 3 + i] =
+ (ret[COL_HINT * 3 + i] + ret[COL_BACKGROUND * 3 + i]) * 0.5F;
+ ret[COL_MARK * 3 + i] = ret[COL_HIGHLIGHT * 3 + i];
+ }
+ ret[COL_WARNING * 3 + 0] = 1.0F;
+ ret[COL_WARNING * 3 + 1] = 0.25F;
+ ret[COL_WARNING * 3 + 2] = 0.25F;
+
+ ret[COL_SELECTED * 3 + 0] = 0.25F;
+ ret[COL_SELECTED * 3 + 1] = 1.00F;
+ ret[COL_SELECTED * 3 + 2] = 0.25F;
+
+ *ncolours = NCOLOURS;
+ return ret;
+}
+
+static game_drawstate *game_new_drawstate(drawing *dr, game_state *state)
+{+ struct game_drawstate *ds = snew(struct game_drawstate);
+ int wh = state->w*state->h;
+
+ ds->tilesize = 0;
+ ds->w = state->w;
+ ds->h = state->h;
+ ds->started = 0;
+ ds->grid = snewn(wh, grid_type);
+ memset(ds->grid, -1, wh*sizeof(grid_type));
+ ds->lv = snewn(wh, int);
+ ds->lh = snewn(wh, int);
+ memset(ds->lv, 0, wh*sizeof(int));
+ memset(ds->lh, 0, wh*sizeof(int));
+
+ return ds;
+}
+
+static void game_free_drawstate(drawing *dr, game_drawstate *ds)
+{+ sfree(ds->lv);
+ sfree(ds->lh);
+ sfree(ds->grid);
+ sfree(ds);
+}
+
+#define LINE_WIDTH (TILE_SIZE/8)
+#define TS8(x) (((x)*TILE_SIZE)/8)
+
+#define OFFSET(thing) ((TILE_SIZE/2) - ((thing)/2))
+
+static void line_vert(drawing *dr, game_drawstate *ds,
+ int ox, int oy, int col, grid_type v)
+{+ int lw = LINE_WIDTH;
+ if (v & G_MARKV)
+ draw_rect(dr, ox-lw, oy, lw*3, TILE_SIZE, COL_MARK);
+ draw_rect(dr, ox, oy, lw, TILE_SIZE, col);
+}
+
+static void line_horiz(drawing *dr, game_drawstate *ds,
+ int ox, int oy, int col, grid_type v)
+{+ int lw = LINE_WIDTH;
+ if (v & G_MARKH)
+ draw_rect(dr, ox, oy-lw, TILE_SIZE, lw*3, COL_MARK);
+ draw_rect(dr, ox, oy, TILE_SIZE, lw, col);
+}
+
+static void line_cross(drawing *dr, game_drawstate *ds,
+ int ox, int oy, int col, grid_type v)
+{+ int off = TS8(2);
+ draw_line(dr, ox, oy, ox+off, oy+off, col);
+ draw_line(dr, ox+off, oy, ox, oy+off, col);
+}
+
+static void lines_lvlh(game_state *state, int x, int y, grid_type v,
+ int *lv_r, int *lh_r)
+{+ int lh = 0, lv = 0;
+
+ if (v & G_LINEV) lv = INDEX(state,lines,x,y);
+ if (v & G_LINEH) lh = INDEX(state,lines,x,y);
+
+#ifdef DRAW_HINTS
+ if (INDEX(state, possv, x, y) && !lv) {+ lv = INDEX(state, possv, x, y);
+ }
+ if (INDEX(state, possh, x, y) && !lh) {+ lh = INDEX(state, possh, x, y);
+ }
+#endif
+ /*debug(("lvlh: (%d,%d) v 0x%x lv %d lh %d.\n", x, y, v, lv, lh));*/+ *lv_r = lv; *lh_r = lh;
+}
+
+static void dsf_debug_draw(drawing *dr,
+ game_state *state, game_drawstate *ds,
+ int x, int y)
+{+#ifdef DRAW_DSF
+ int ts = TILE_SIZE/2;
+ int ox = COORD(x) + ts/2, oy = COORD(y) + ts/2;
+ char str[10];
+
+ sprintf(str, "%d", dsf_canonify(state->solver->dsf, DINDEX(x,y)));
+ draw_text(dr, ox, oy, FONT_VARIABLE, ts,
+ ALIGN_VCENTRE | ALIGN_HCENTRE, COL_WARNING, str);
+#endif
+}
+
+static void lines_redraw(drawing *dr,
+ game_state *state, game_drawstate *ds, game_ui *ui,
+ int x, int y, grid_type v, int lv, int lh)
+{+ int lw = LINE_WIDTH, bw;
+ int ox = COORD(x), oy = COORD(y), loff, i;
+ int vcol = (v & G_FLASH) ? COL_HIGHLIGHT :
+ (v & G_WARN) ? COL_WARNING : COL_FOREGROUND, hcol = vcol;
+ grid_type todraw = v & G_NOLINE;
+
+ if (v & G_ISSEL) {+ if (ui->todraw & G_FLAGSH) hcol = COL_SELECTED;
+ if (ui->todraw & G_FLAGSV) vcol = COL_SELECTED;
+ todraw |= ui->todraw;
+ }
+
+ draw_rect(dr, ox, oy, TILE_SIZE, TILE_SIZE, COL_BACKGROUND);
+
+#ifdef DRAW_HINTS
+ if (INDEX(state, possv, x, y) && !(v & G_LINEV))
+ vcol = COL_HINT;
+ if (INDEX(state, possh, x, y) && !(v & G_LINEH))
+ hcol = COL_HINT;
+#endif
+#ifdef DRAW_GRID
+ draw_rect_outline(dr, ox, oy, TILE_SIZE, TILE_SIZE, COL_GRID);
+#endif
+
+ if (todraw & G_NOLINEV) {+ line_cross(dr, ds, ox + TS8(3), oy + TS8(1), vcol, todraw);
+ line_cross(dr, ds, ox + TS8(3), oy + TS8(5), vcol, todraw);
+ }
+ if (todraw & G_NOLINEH) {+ line_cross(dr, ds, ox + TS8(1), oy + TS8(3), hcol, todraw);
+ line_cross(dr, ds, ox + TS8(5), oy + TS8(3), hcol, todraw);
+ }
+ if (lv) {+ bw = (lv*2-1) * lw;
+ for (i = 0, loff = OFFSET(bw); i < lv; i++, loff += lw*2)
+ line_vert(dr, ds, ox + loff, oy, vcol, v);
+ }
+ if (lh) {+ bw = (lh*2-1) * lw;
+ for (i = 0, loff = OFFSET(bw); i < lh; i++, loff += lw*2)
+ line_horiz(dr, ds, ox, oy + loff, hcol, v);
+ }
+
+ dsf_debug_draw(dr, state, ds, x, y);
+ draw_update(dr, ox, oy, TILE_SIZE, TILE_SIZE);
+}
+
+#define ISLAND_RADIUS ((TILE_SIZE*13)/20)
+#define ISLAND_NUMSIZE(is) \
+ (((is)->count < 10) ? TILE_SIZE : (TILE_SIZE*8)/10)
+
+static void island_redraw(drawing *dr,
+ game_state *state, game_drawstate *ds,
+ struct island *is, grid_type v)
+{+ /* These overlap the edges of their squares, which is why they're drawn later.
+ * We know they can't overlap each other because they're not allowed within 2
+ * squares of each other. */
+ int half = TILE_SIZE/2;
+ int ox = COORD(is->x) + half, oy = COORD(is->y) + half;
+ int orad = ISLAND_RADIUS, irad = orad - LINE_WIDTH;
+ int updatesz = orad*2+1;
+ int tcol = (v & G_FLASH) ? COL_HIGHLIGHT :
+ (v & G_WARN) ? COL_WARNING : COL_FOREGROUND;
+ int col = (v & G_ISSEL) ? COL_SELECTED : tcol;
+ int bg = (v & G_MARK) ? COL_MARK : COL_BACKGROUND;
+ char str[10];
+
+#ifdef DRAW_GRID
+ draw_rect_outline(dr, COORD(is->x), COORD(is->y),
+ TILE_SIZE, TILE_SIZE, COL_GRID);
+#endif
+
+ /* draw a thick circle */
+ draw_circle(dr, ox, oy, orad, col, col);
+ draw_circle(dr, ox, oy, irad, bg, bg);
+
+ sprintf(str, "%d", is->count);
+ draw_text(dr, ox, oy, FONT_VARIABLE, ISLAND_NUMSIZE(is),
+ ALIGN_VCENTRE | ALIGN_HCENTRE, tcol, str);
+
+ dsf_debug_draw(dr, state, ds, is->x, is->y);
+ draw_update(dr, ox - orad, oy - orad, updatesz, updatesz);
+}
+
+static void game_redraw(drawing *dr, game_drawstate *ds, game_state *oldstate,
+ game_state *state, int dir, game_ui *ui,
+ float animtime, float flashtime)
+{+ int x, y, force = 0, i, j, redraw, lv, lh;
+ grid_type v, dsv, flash = 0;
+ struct island *is, *is_drag_src = NULL, *is_drag_dst = NULL;
+
+ if (flashtime) {+ int f = (int)(flashtime * 5 / FLASH_TIME);
+ if (f == 1 || f == 3) flash = G_FLASH;
+ }
+
+ /* Clear screen, if required. */
+ if (!ds->started) {+ draw_rect(dr, 0, 0,
+ TILE_SIZE * ds->w + 2 * BORDER,
+ TILE_SIZE * ds->h + 2 * BORDER, COL_BACKGROUND);
+#ifdef DRAW_GRID
+ draw_rect_outline(dr,
+ COORD(0)-1, COORD(0)-1,
+ TILE_SIZE * ds->w + 2, TILE_SIZE * ds->h + 2,
+ COL_GRID);
+#endif
+ draw_update(dr, 0, 0,
+ TILE_SIZE * ds->w + 2 * BORDER,
+ TILE_SIZE * ds->h + 2 * BORDER);
+ ds->started = 1;
+ force = 1;
+ }
+
+ if (ui->dragx_src != -1 && ui->dragy_src != -1) {+ ds->dragging = 1;
+ is_drag_src = INDEX(state, gridi, ui->dragx_src, ui->dragy_src);
+ assert(is_drag_src);
+ if (ui->dragx_dst != -1 && ui->dragy_dst != -1) {+ is_drag_dst = INDEX(state, gridi, ui->dragx_dst, ui->dragy_dst);
+ assert(is_drag_dst);
+ }
+ } else
+ ds->dragging = 0;
+
+ /* Draw all lines (and hints, if we want), but *not* islands. */
+ for (x = 0; x < ds->w; x++) {+ for (y = 0; y < ds->h; y++) {+ v = GRID(state, x, y) | flash;
+ dsv = GRID(ds,x,y) & ~G_REDRAW;
+
+ if (v & G_ISLAND) continue;
+
+ if (is_drag_dst) {+ if (WITHIN(x,is_drag_src->x, is_drag_dst->x) &&
+ WITHIN(y,is_drag_src->y, is_drag_dst->y))
+ v |= G_ISSEL;
+ }
+ lines_lvlh(state, x, y, v, &lv, &lh);
+
+ if (v != dsv ||
+ lv != INDEX(ds,lv,x,y) ||
+ lh != INDEX(ds,lh,x,y) ||
+ force) {+ GRID(ds, x, y) = v | G_REDRAW;
+ INDEX(ds,lv,x,y) = lv;
+ INDEX(ds,lh,x,y) = lh;
+ lines_redraw(dr, state, ds, ui, x, y, v, lv, lh);
+ } else
+ GRID(ds,x,y) &= ~G_REDRAW;
+ }
+ }
+
+ /* Draw islands. */
+ for (i = 0; i < state->n_islands; i++) {+ is = &state->islands[i];
+ v = GRID(state, is->x, is->y) | flash;
+
+ redraw = 0;
+ for (j = 0; j < is->adj.npoints; j++) {+ if (GRID(ds,is->adj.points[j].x,is->adj.points[j].y) & G_REDRAW) {+ redraw = 1;
+ }
+ }
+
+ if (is_drag_src) {+ if (is == is_drag_src)
+ v |= G_ISSEL;
+ else if (is_drag_dst && is == is_drag_dst)
+ v |= G_ISSEL;
+ }
+
+ if (island_impossible(is, v & G_MARK)) v |= G_WARN;
+
+ if ((v != GRID(ds, is->x, is->y)) || force || redraw) {+ GRID(ds,is->x,is->y) = v;
+ island_redraw(dr, state, ds, is, v);
+ }
+ }
+}
+
+static float game_anim_length(game_state *oldstate, game_state *newstate,
+ int dir, game_ui *ui)
+{+ return 0.0F;
+}
+
+static float game_flash_length(game_state *oldstate, game_state *newstate,
+ int dir, game_ui *ui)
+{+ if (!oldstate->completed && newstate->completed &&
+ !oldstate->solved && !newstate->solved)
+ return FLASH_TIME;
+
+ return 0.0F;
+}
+
+static int game_wants_statusbar(void)
+{+ return FALSE;
+}
+
+static int game_timing_state(game_state *state, game_ui *ui)
+{+ return TRUE;
+}
+
+static void game_print_size(game_params *params, float *x, float *y)
+{+ int pw, ph;
+
+ /* 10mm squares by default. */
+ game_compute_size(params, 1000, &pw, &ph);
+ *x = pw / 100.0;
+ *y = ph / 100.0;
+}
+
+static void game_print(drawing *dr, game_state *state, int ts)
+{+ int ink = print_mono_colour(dr, 0);
+ int paper = print_mono_colour(dr, 1);
+ int x, y, cx, cy, i, nl;
+ int loff = ts/8;
+ grid_type grid;
+
+ /* Ick: fake up `ds->tilesize' for macro expansion purposes */
+ game_drawstate ads, *ds = &ads;
+ ads.tilesize = ts;
+
+ /* I don't think this wants a border. */
+
+ /* Bridges */
+ print_line_width(dr, ts / 12);
+ for (x = 0; x < state->w; x++) {+ for (y = 0; y < state->h; y++) {+ cx = COORD(x); cy = COORD(y);
+ grid = GRID(state,x,y);
+ nl = INDEX(state,lines,x,y);
+
+ if (grid & G_ISLAND) continue;
+ if (grid & G_LINEV) {+ if (nl > 1) {+ draw_line(dr, cx+ts/2-loff, cy, cx+ts/2-loff, cy+ts, ink);
+ draw_line(dr, cx+ts/2+loff, cy, cx+ts/2+loff, cy+ts, ink);
+ } else {+ draw_line(dr, cx+ts/2, cy, cx+ts/2, cy+ts, ink);
+ }
+ }
+ if (grid & G_LINEH) {+ if (nl > 1) {+ draw_line(dr, cx, cy+ts/2-loff, cx+ts, cy+ts/2-loff, ink);
+ draw_line(dr, cx, cy+ts/2+loff, cx+ts, cy+ts/2+loff, ink);
+ } else {+ draw_line(dr, cx, cy+ts/2, cx+ts, cy+ts/2, ink);
+ }
+ }
+ }
+ }
+
+ /* Islands */
+ for (i = 0; i < state->n_islands; i++) {+ char str[10];
+ struct island *is = &state->islands[i];
+ grid = GRID(state, is->x, is->y);
+ cx = COORD(is->x) + ts/2;
+ cy = COORD(is->y) + ts/2;
+
+ draw_circle(dr, cx, cy, ISLAND_RADIUS, paper, ink);
+
+ sprintf(str, "%d", is->count);
+ draw_text(dr, cx, cy, FONT_VARIABLE, ISLAND_NUMSIZE(is),
+ ALIGN_VCENTRE | ALIGN_HCENTRE, ink, str);
+ }
+}
+
+#ifdef COMBINED
+#define thegame bridges
+#endif
+
+const struct game thegame = {+ "Bridges", "games.bridges",
+ default_params,
+ game_fetch_preset,
+ decode_params,
+ encode_params,
+ free_params,
+ dup_params,
+ TRUE, game_configure, custom_params,
+ validate_params,
+ new_game_desc,
+ validate_desc,
+ new_game,
+ dup_game,
+ free_game,
+ TRUE, solve_game,
+ TRUE, game_text_format,
+ new_ui,
+ free_ui,
+ encode_ui,
+ decode_ui,
+ game_changed_state,
+ interpret_move,
+ execute_move,
+ PREFERRED_TILE_SIZE, game_compute_size, game_set_size,
+ game_colours,
+ game_new_drawstate,
+ game_free_drawstate,
+ game_redraw,
+ game_anim_length,
+ game_flash_length,
+ TRUE, FALSE, game_print_size, game_print,
+ game_wants_statusbar,
+ FALSE, game_timing_state,
+ 0, /* mouse_priorities */
+};
+
+/* vim: set shiftwidth=4 tabstop=8: */
--- a/list.c
+++ b/list.c
@@ -18,6 +18,7 @@
*/
extern const game blackbox;
+extern const game bridges;
extern const game cube;
extern const game dominosa;
extern const game fifteen;
@@ -43,6 +44,7 @@
const game *gamelist[] = {&blackbox,
+ &bridges,
&cube,
&dominosa,
&fifteen,
--- a/puzzles.but
+++ b/puzzles.but
@@ -1859,6 +1859,135 @@
available difficulty levels requires guesswork or backtracking.
+\C{bridges} \i{Bridges}+
+\cfg{winhelp-topic}{games.bridges}+
+You have a set of islands distributed across the playing area. Each
+island contains a number. Your aim is to connect the islands
+together with bridges, in such a way that:
+
+\b Bridges run horizontally or vertically.
+
+\b The number of bridges terminating at any island is equal to the
+number written in that island.
+
+\b Two bridges may run in parallel between the same two islands, but
+no more than two may do so.
+
+\b No bridge crosses another bridge.
+
+\b All the islands are connected together.
+
+There are some configurable alternative modes, which involve
+changing the parallel-bridge limit to something other than 2, and
+introducing the additional constraint that no sequence of bridges
+may form a loop from one island back to the same island. The rules
+stated above are the default ones.
+
+Credit for this puzzle goes to \i{Nikoli} \k{nikoli-bridges}.+
+Bridges was contributed to this collection by James Harvey.
+
+\B{nikoli-bridges}+\W{http://www.nikoli.co.jp/puzzles/14/index-e.htm}\cw{http://www.nikoli.co.jp/puzzles/14/index-e.htm}+
+\H{bridges-controls} \i{Bridges controls}+
+\IM{Bridges controls} controls, for Bridges+
+To place a bridge between two islands, click the mouse down on one
+island and drag it towards the other. You do not need to drag all
+the way to the other island; you only need to move the mouse far
+enough for the intended bridge direction to be unambiguous. (So you
+can keep the mouse near the starting island and conveniently throw
+bridges out from it in many directions.)
+
+Doing this again when a bridge is already present will add another
+parallel bridge. If there are already as many bridges between the
+two islands as permitted by the current game rules (i.e. two by
+default), the same dragging action will remove all of them.
+
+If you want to remind yourself that two islands definitely \e{do+not} have a bridge between them, you can right-drag between them in
+the same way to draw a \q{non-bridge} marker.+
+If you think you have finished with an island (i.e. you have placed
+all its bridges and are confident that they are in the right
+places), you can mark the island as finished by left-clicking on it.
+This will highlight it and all the bridges connected to it, and you
+will be prevented from accidentally modifying any of those bridges
+in future. Left-clicking again on a highlighted island will unmark
+it and restore your ability to modify it.
+
+Violations of the puzzle rules will be marked in red:
+
+\b An island with too many bridges will be highlighted in red.
+
+\b An island with too few bridges will be highlighted in red if it
+is definitely an error (as opposed to merely not being finished
+yet): if adding enough bridges would involve having to cross another
+bridge or remove a non-bridge marker, or if the island has been
+highlighted as complete.
+
+\b A group of islands and bridges may be highlighted in red if it is
+a closed subset of the puzzle with no way to connect it to the rest
+of the islands. For example, if you directly connect two 1s together
+with a bridge and they are not the only two islands on the grid,
+they will light up red to indicate that such a group cannot be
+contained in any valid solution.
+
+\b If you have selected the (non-default) option to disallow loops
+in the solution, a group of bridges which forms a loop will be
+highlighted.
+
+(All the actions described in \k{common-actions} are also available.)+
+\H{bridges-parameters} \I{parameters, for Bridges}Bridges parameters+
+These parameters are available from the \q{Custom...} option on the+\q{Type} menu.+
+\dt \e{Width}, \e{Height}+
+\dd Size of grid in squares.
+
+\dt \e{Difficulty}+
+\dd Difficulty level of puzzle.
+
+\dt \e{Allow loops}+
+\dd This is set by default. If cleared, puzzles will be generated in
+such a way that they are always soluble without creating a loop, and
+solutions which do involve a loop will be disallowed.
+
+\dt \e{Max. bridges per direction}+
+\dd Maximum number of bridges in any particular direction. The
+default is 2, but you can change it to 1, 3 or 4. In general, fewer
+is easier.
+
+\dt \e{%age of island squares}+
+\dd Gives a rough percentage of islands the generator will try and
+lay before finishing the puzzle. Certain layouts will not manage to
+lay enough islands; this is an upper bound.
+
+\dt \e{Expansion factor (%age)}+
+\dd The grid generator works by picking an existing island at random
+(after first creating an initial island somewhere). It then decides
+on a direction (at random), and then works out how far it could
+extend before creating another island. This parameter determines how
+likely it is to extend as far as it can, rather than choosing
+somewhere closer.
+
+High expansion factors usually mean easier puzzles with fewer
+possible islands; low expansion factors can create lots of
+tightly-packed islands.
+
+
\A{licence} \I{MIT licence}\ii{Licence} This software is \i{copyright} 2004-2005 Simon Tatham.