Create: 0036-valid-sudoku.dart

dart/0036-valid-sudoku.dart

@@ -0,0 +1,31 @@
+// As the board size is fixed
+// it will result in the following
+// Time Complexity: O(1)
+// Space Complexity: O(1)
+
+class Solution {
+ bool isValidSudoku(List<List<String>> board) {
+ var rows = List.filled(9, 0);
+ var cols = List.filled(9, 0);
+ var grids = List.filled(9, 0);
+
+ for (int r = 0; r < 9; r++) {
+ for (int c = 0; c < 9; c++) {
+ if (board[r][c] == ".") continue;
+
+ var idx = int.parse(board[r][c]) - 1;
+
+ if (rows[r] & 1 << idx != 0) return false;
+ rows[r] |= 1 << idx;
+
+ if (cols[c] & 1 << idx != 0) return false;
+ cols[c] |= 1 << idx;
+
+ if (grids[r ~/ 3 * 3 + c ~/ 3] & 1 << idx != 0) return false;
+ grids[r ~/ 3 * 3 + c ~/ 3] |= 1 << idx;
+ }
+ }
+
+ return true;
+ }
+}