ref: f061101210352b9783085ba37e1c58f1fac89862
parent: d1219cac3c2e0adf58a477e442a8656bcb55ed0f
author: Simon Tatham <anakin@pobox.com>
date: Fri Dec 11 13:09:41 EST 2015
Pattern: add a system of immutable pre-filled grid squares. The game previously only supported numeric clues round the edge; but if for some reason you really want a puzzle with a specific solution bitmap and that bitmap doesn't happen to be uniquely soluble from only its row and column counts, then this gives you a fallback approach of pre-filling a few grid squares to resolve the ambiguities. (This also applies if the puzzle is uniquely soluble *in principle* but not by Pattern's limited solver - for example, Pattern has never been able to solve 4x4:2/1/2/1/1.1/2/1/1 and still can't, but now it can solve 4x4:2/1/2/1/1.1/2/1/1,Ap which has the hard part done for it.) Immutable squares are protected from modification during play, and used as initial information by the solver.