From fb99a391331f49544b2842f6babd34f18a645e40 Mon Sep 17 00:00:00 2001 From: simon Date: Sun, 21 Mar 2010 08:48:29 +0000 Subject: [PATCH] Error highlighting bug in Bridges: when counting the number of extra bridges that could go to an island, the game was not correctly accounting for existing bridges in all circumstances. (E.g. in 7x7m2:2a6a2a1g4a6c4i1a1h23c2b, connect the top right 1 to the 2 left of it, and the 6 left of that correctly lights up red. But now connect the 6 to the 6 below it, and it wrongly unlights again.) git-svn-id: svn://svn.tartarus.org/sgt/puzzles@8905 cda61777-01e9-0310-a592-d414129be87e --- bridges.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/bridges.c b/bridges.c index 5bb73f4..4219df4 100644 --- a/bridges.c +++ b/bridges.c @@ -542,9 +542,24 @@ static int island_impossible(struct island *is, int strict) 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 (ifree > 0) { + /* + * ifree is the number of bridges unfilled in the other + * island, which is clearly an upper bound on the number + * of extra bridges this island may run to it. + * + * Another upper bound is the number of bridges unfilled + * on the specific line between here and there. We must + * take the minimum of both. + */ + int bmax = MAXIMUM(is->state, dx, + is->adj.points[i].x, is->adj.points[i].y); + int bcurr = GRIDCOUNT(is->state, + is->adj.points[i].x, is->adj.points[i].y, + dx ? G_LINEH : G_LINEV); + assert(bcurr <= bmax); + nsurrspc += min(ifree, bmax - bcurr); + } } if (nsurrspc < nspc) { debug(("island at (%d,%d) impossible: surr. islands %d spc, need %d.\n", -- 2.11.0