is valid sudoku today

Author: LEUNGUU

src/is_valid_sudoku.py

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+from typing import List
+from collections import defaultdict
+
+
+class Solution:
+    def isValidSudoku(self, board: List[List[str]]) -> bool:
+        rows = defaultdict(set)
+        cols = defaultdict(set)
+        subbox = defaultdict(set)  # key is r//3, c//3
+
+        for r in range(9):
+            for c in range(9):
+                if board[r][c] == ".":
+                    continue
+                if (
+                    board[r][c] in rows[r]
+                    or board[r][c] in cols[c]
+                    or board[r][c] in subbox[(r // 3, c // 3)]
+                ):
+                    return False
+                rows[r].add(board[r][c])
+                cols[c].add(board[r][c])
+                subbox[(r // 3, c // 3)].add(board[r][c])
+        return True

tests/test_valid_sudoku.py

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+from is_valid_sudoku import Solution
+
+testcases = [
+    {
+        "testcase": [
+            ["5", "3", ".", ".", "7", ".", ".", ".", "."],
+            ["6", ".", ".", "1", "9", "5", ".", ".", "."],
+            [".", "9", "8", ".", ".", ".", ".", "6", "."],
+            ["8", ".", ".", ".", "6", ".", ".", ".", "3"],
+            ["4", ".", ".", "8", ".", "3", ".", ".", "1"],
+            ["7", ".", ".", ".", "2", ".", ".", ".", "6"],
+            [".", "6", ".", ".", ".", ".", "2", "8", "."],
+            [".", ".", ".", "4", "1", "9", ".", ".", "5"],
+            [".", ".", ".", ".", "8", ".", ".", "7", "9"],
+        ],
+        "result": True,
+    }
+]
+
+
+def test_is_valid_sudoku():
+    for tc in testcases:
+        board = tc["testcase"]
+        ans = Solution().isValidSudoku(board)
+        assert ans == tc["result"]