pythonSnippets/validSudoku.py at main · dangerousLefty/pythonSnippets · GitHub

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import collections


def isValidSudoku(board: list[list[str]]) -> bool:
    cols = collections.defaultdict(list)
    rows = collections.defaultdict(list)
    squares = collections.defaultdict(list)

    for r in range(9):
        for c in range(9):
            if board[r][c] != ".":
                if (board[r][c] in rows[r] or
                    board[r][c] in cols[c] or
                        board[r][c] in squares[(r // 3, c // 3)]):
                    return False
                cols[c].append(board[r][c])
                rows[r].append(board[r][c])
                squares[(r // 3, c // 3)].append(board[r][c])
    return True


board = [["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"]]

print(isValidSudoku(board))