LeetCode：36. 有效的数独（Python 3）

最新推荐文章于 2024-12-03 15:36:08 发布

SoulOH

最新推荐文章于 2024-12-03 15:36:08 发布

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分类专栏： LeetCode 文章标签： LeetCode 数组

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题目：

判断一个 9x9 的数独是否有效。只需要根据以下规则，验证已经填入的数字是否有效即可。

数字 1-9 在每一行只能出现一次。
数字 1-9 在每一列只能出现一次。
数字 1-9 在每一个以粗实线分隔的 3x3 宫内只能出现一次。

上图是一个部分填充的有效的数独。

数独部分空格内已填入了数字，空白格用 '.' 表示。

示例 1:

输入:
[
  ["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"]
]
输出: true

示例 2:

输入:
[
  ["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"]
]
输出: false
解释: 除了第一行的第一个数字从 5 改为 8 以外，空格内其他数字均与 示例1 相同。
     但由于位于左上角的 3x3 宫内有两个 8 存在, 因此这个数独是无效的。

说明:

一个有效的数独（部分已被填充）不一定是可解的。
只需要根据以上规则，验证已经填入的数字是否有效即可。
给定数独序列只包含数字 1-9 和字符 '.' 。
给定数独永远是 9x9 形式的。

解答：

这次直接给代码：

class Solution:
    def isValidSudoku(self, board):
        """
        :type board: List[List[str]]
        :rtype: bool
        """
        return self.isValidRow(board) and self.isValidColumn(board) and self.isValidSquare(board)
        
    def isValidRow(self, board):
        for i in board:
            if not self.isValidUnit(i):
                return False
        return True
    
    def isValidColumn(self, board):
        for i in list(zip(*board)):
            if not self.isValidUnit(i):
                return False
        return True
        
    def isValidSquare(self, board):
        for i in (0, 3, 6):
            for j in (0, 3, 6):
                square = [board[x][y] for x in range(i, i+3) for y in range(j , j + 3)]
                if not self.isValidUnit(square):
                    return False
        return True
        
    def isValidUnit(self, unit):
        unit = [i for i in unit if i != "."]
        return len(set(unit)) == len(unit)

参考资料：https://leetcode.com/problems/valid-sudoku/discuss/15451/A-readable-Python-solution，