From e6b4800d86cfc5e1bfc5e3b5bde78a182f6fe5b2 Mon Sep 17 00:00:00 2001
From: Simon Tatham <anakin@pobox.com>
Date: Thu, 2 Feb 2012 23:04:43 +0000
Subject: [PATCH] Don't try to run solver_killer_sums on a Killer cage with
 only one square. It isn't equipped for it, and will try to handle it with the
 4-square case and get confused. This can come up if the DIFF_KINTERSECT pass
 before that split a cage, and will cause the solver to miss valid solutions;
 e.g. 3x3kadu#802065940985372 would generate an ambiguous puzzle before this
 change.

[originally from svn r9402]
---
 solo.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/solo.c b/solo.c
index 766adde..6987872 100644
--- a/solo.c
+++ b/solo.c
@@ -1473,7 +1473,7 @@ static int solver_killer_sums(struct solver_usage *usage, int b,
     }
     assert(nsquares > 0);
 
-    if (nsquares > 4)
+    if (nsquares < 2 || nsquares > 4)
 	return 0;
 
     if (!cage_is_region) {