shithub: kwa

ref: 8f2d3879a9c66d2633ca7ec1c3b0495981feb04f
dir: /test/t.randk/

{
	k = 2
	n = NF
	i = 1
	while ( i <= n ) {
		if ( rand() < k/n ) {
			print i
			k--
		}
		n--
		i++
	}
}