From 058dc13c1c43c7dfad7cd91f453b975bb26d8d50 Mon Sep 17 00:00:00 2001
From: Matt Low <matt@mlow.ca>
Date: Thu, 25 Feb 2021 00:49:41 -0700
Subject: [PATCH] Simplified selectColumnSizeHeuristic

---
 src/sudoku/dlx.ts | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/src/sudoku/dlx.ts b/src/sudoku/dlx.ts
index 1eb9f49..dd076e2 100644
--- a/src/sudoku/dlx.ts
+++ b/src/sudoku/dlx.ts
@@ -33,18 +33,13 @@ type SolutionCallback = (output: DNode[]) => boolean;
 type ColumnSelector = (header: CNode) => CNode;
 
 function selectColumnSizeHeuristic(header: CNode): CNode {
-  let minSize = Infinity;
-  let minColumn: CNode | undefined;
-  let curColumn = header;
+  let minColumn = header.right;
+  let curColumn = minColumn;
   while ((curColumn = curColumn.right) !== header) {
-    if (curColumn.column.size < minSize) {
-      minSize = curColumn.column.size;
+    if (curColumn.size < minColumn.size) {
       minColumn = curColumn;
     }
   }
-  if (!minColumn) {
-    throw new Error("minColumn is undefined, this shouldn't be possible.");
-  }
   return minColumn;
 }