From 46f470821b0cd9cba05f5539102a0a0583258e41 Mon Sep 17 00:00:00 2001
From: mxhagen <markichnich@proton.me>
Date: Tue, 24 Sep 2024 18:40:02 +0200
Subject: [PATCH] fix validation of 3x3 blocks

---
 src/sudoku/validator.rs |  2 +-
 src/tests/validator.rs  | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/sudoku/validator.rs b/src/sudoku/validator.rs
index 256e9f2..7ba5db5 100644
--- a/src/sudoku/validator.rs
+++ b/src/sudoku/validator.rs
@@ -22,7 +22,7 @@ pub fn is_solution(sudoku: &Board) -> bool {
         let mut block_set = 0u16;
         for j in 0..9 {
             let tmp = block_set;
-            block_set ^= 1 << sudoku[i / 3 * 3 + i % 3][j / 3 * 3 + j % 3];
+            block_set ^= 1 << sudoku[i / 3 * 3 + j / 3][i % 3 * 3 + j % 3];
             if block_set < tmp {
                 return false;
             }
diff --git a/src/tests/validator.rs b/src/tests/validator.rs
index 77655f8..e33cfef 100644
--- a/src/tests/validator.rs
+++ b/src/tests/validator.rs
@@ -47,3 +47,19 @@ fn invalid_unfinished() {
     ];
     assert!(!is_solution(&board));
 }
+
+#[test]
+fn invalid_blocks_wrong() {
+    let board = [
+        [5, 6, 9, 3, 7, 8, 1, 2, 4],
+        [7, 4, 3, 1, 2, 9, 6, 5, 8],
+        [4, 5, 1, 6, 8, 2, 9, 7, 3],
+        [9, 8, 6, 7, 4, 5, 3, 1, 2],
+        [6, 3, 7, 2, 5, 1, 4, 8, 9],
+        [8, 9, 2, 4, 1, 3, 7, 6, 5],
+        [3, 1, 8, 5, 6, 4, 2, 9, 7],
+        [2, 7, 4, 8, 9, 6, 5, 3, 1],
+        [1, 2, 5, 9, 3, 7, 8, 4, 6],
+    ];
+    assert!(!is_solution(&board));
+}