From: Stefan Bühler <stbuehler@web.de>
Date: Sat, 7 Oct 2017 21:21:45 +0000 (+0200)
Subject: fix loop condition
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ian/git?a=commitdiff_plain;h=00e23909f8599686ae8aa975a7f5a443a500516f;p=sgt-puzzles.git

fix loop condition

prev[sink] == 0 means there was a path found with the last step being a
forward edge to the sink, and the edge being at index 0 in the array.

This is a valid path (the same as any other path indicated by prev[sink]
> 0).
---

diff --git a/maxflow.c b/maxflow.c
index 028946b..97ae8c4 100644
--- a/maxflow.c
+++ b/maxflow.c
@@ -80,7 +80,7 @@ int maxflow_with_scratch(void *scratch, int nv, int source, int sink,
 	/*
 	 * Now do the BFS loop.
 	 */
-	while (head < tail && prev[sink] <= 0) {
+	while (head < tail && prev[sink] < 0) {
 	    from = todo[head++];
 
 	    /*