題目描述

判斷一個 9x9 的數獨是否有效。只需要根據以下規則，驗證已經填入的數字是否有效即可。

1. 數字 1-9 在每一行只能出現一次。
2. 數字 1-9 在每一列只能出現一次。
3. 數字 1-9 在每一個以粗實線分隔的 3x3 宮內只能出現一次。

上圖是一個部分填充的有效的數獨。

數獨部分空格內已填入了數字，空白格用 '.' 表示。

示例 1:

輸入:
[
  ["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"]
]
輸出:
 
 true

示例 2:

輸入:
[
  ["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"]
]
輸出:
 
 false
解釋: 除了第一行的第一個數字從 5 改為 8 以外，空格內其他數字均與 示例1 相同。
     但由於位於左上角的 3x3 宮內有兩個 8 存在, 因此這個數獨是無效的。

說明:

• 一個有效的數獨（部分已被填充）不一定是可解的。
• 只需要根據以上規則，驗證已經填入的數字是否有效即可。
• 給定數獨序列只包含數字 1-9 和字元 '.' 。
• 給定數獨永遠是 9x9 形式的。

題目理解

題目的目的是完成查詢這個數獨是否有效，所以需要判斷三種類型：1.每個3*3的宮格是否有效；2.每行9個宮格是否有效；3.每列9個宮格是否有效。如果都有效，說明此刻是有效的數獨。

程式碼（py）

class Solution(object):
    def isValidSudoku(self, board):
        """
        :type board: List[List[str]]
        :rtype: bool
        """
        # 3*3 * 9
        for i in range(3):
            for j in range(3):
                temp = [0 for tt in range(0,10)]
                for k in range(3):
                    for l in range(3):
                        tt = board[i*3+k][j*3+l]
                        if tt != '.':
                            tt = int(tt)
                            if temp[tt] == 0:
                                temp[tt] = 1
                            else:
                                return False
        # 9 row
        for i in range(9):
            temp = [0 for tt in range(0,10)]
            for j in range(9):
                tt = board[i][j]
                if tt != '.':
                    tt = int(tt)
                    if temp[tt] == 0:
                        temp[tt] = 1
                    else:
                        return False
        # 9 col
        for i in range(9):
            temp = [0 for tt in range(0,10)]
            for j in range(9):
                tt = board[j][i]
                if tt != '.':
                    tt = int(tt)
                    if temp[tt] == 0:
                        temp[tt] = 1
                    else:
                        return False
        return True
 

程式碼分析：根據三種類型的數獨判定方式來判斷，然後使用一個list來作為鍵值判斷標記。如果出現過，就標記為1，如果再次出現，說明數獨是有問題的，就返回False。