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Diffstat (limited to 'valid_sudoku.py')
-rw-r--r-- | valid_sudoku.py | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/valid_sudoku.py b/valid_sudoku.py new file mode 100644 index 0000000..8dd758a --- /dev/null +++ b/valid_sudoku.py @@ -0,0 +1,59 @@ +# 36. Valid Sudoku + +""" +determine if a 9 x 9 sudoku board is valid. only the filled cells need to be +validated acording to the following rules. each row must contain the digits +1-9 without repetition, each column must contain the digits 1-9 without +reptition, each of the nine 3 x 3 sub-boxes of the grid must contain the +digits 1-9 without reptition. note, a sudoku board (partially filled) could +be valid but it is not necessarily solvable. only the filled cells need to be +validated according to the mentioned rules. +""" + + +class Solution(object): + def isValidSudoku(self, board): + """ + :type board: List[List[str]] + :rtype: bool + """ + rows = [[False] * 9 for _ in range(9)] + cols = [[False] * 9 for _ in range(9)] + boxes = [[False] * 9 for _ in range(9)] + for i in range(9): + for j in range(9): + if board[i][j] != ".": + num = ord(board[i][j] - ord("1")) + box_idx = (i // 3) * 3 + (j // 3) + if rows[i][num] or cols[j][num] or boxes[box_idx][num]: + return False + rows[i][num] = cols[j][num] = boxes[box_idx][num] = True + return True + + +if __name__ == "__main__": + obj = Solution() + b1 = [ + ["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"], + ] + b2 = [ + ["8", "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(obj.isValidSudoku(b1)) + print(obj.isValidSudoku(b2)) |