From: Simon Tatham <anakin@pobox.com>
Date: Sat, 8 Mar 2014 00:19:41 +0000 (+0000)
Subject: Prune by symmetry: constrain 1st adj row to all 1s at low end.
X-Git-Tag: v1
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=matchsticks-search.git;a=commitdiff_plain;h=0169095a9c345a65ee9e091df63a0e52d3910d1d

Prune by symmetry: constrain 1st adj row to all 1s at low end.
---

diff --git a/main.c b/main.c
index 83728fa..6f0df72 100644
--- a/main.c
+++ b/main.c
@@ -329,6 +329,8 @@ static void iterate_recurse(int i, AdjWord min) {
        adjmatrix[i]++) {
     if (count_set_adj_bits(adjmatrix[i]) > maxhamweight)
       goto again;
+    if (i == 0 && (adjmatrix[i] & (1+adjmatrix[i])))
+      goto again;
 
     iterate_recurse(i+1, adjmatrix[i]);