1 files changed, 7 insertions, 9 deletions

diff --git a/board.cpp b/board.cpp
index 91655dc..bd56f8a 100644
--- a/board.cpp
+++ b/board.cpp
@@ -160,15 +160,13 @@ const vector<int>& Board::getEdgeCells() const {
 Bounds Board::computeBounds() const {
 	Bounds bounds;
 
-	for (int y = 1; y < BSZ - 1; y++) {
-		for (int x = 1; x < BSZ - 1; x++) {
-			int idx = BSZ * y + x;
-			if (bd[idx] != 0 || checkEdge(idx)) {
-				bounds.left = min(bounds.left, x);
-				bounds.right = max(bounds.right, x);
-				bounds.top = min(bounds.top, y);
-				bounds.bottom = max(bounds.bottom, y);
-			}
+	for (int idx : edgeCells) {
+		int x = idx % BSZ, y = idx / BSZ;
+		if (bd[idx] != 0 || checkEdge(idx)) {
+			bounds.left = min(bounds.left, x);
+			bounds.right = max(bounds.right, x);
+			bounds.top = min(bounds.top, y);
+			bounds.bottom = max(bounds.bottom, y);
 		}
 	}