[leetcode] 36. Valid Sudoku

[leetcode] 36. Valid Sudoku

Description

Determine if a 9x9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:

Each row must contain the digits 1-9 without repetition.Each column must contain the digits 1-9 without repetition.Each of the 9 3x3 sub-boxes of the grid must contain the digits 1-9 without repetition.

A partially filled sudoku which is valid.

The Sudoku board could be partially filled, where empty cells are filled with the character ‘.’.

Example 1:

Input:

[ ["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"]]

Output:

true

Example 2:

Input:

[ ["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"]]

Output:

false

Explanation:

Same as Example 1, except with the 5 in the top left corner being modified to 8. Since there are two 8's in the top left 3x3 sub-box, it is invalid.

Note:

A Sudoku board (partially filled) could be valid but is not necessarily solvable.Only the filled cells need to be validated according to the mentioned rules.The given board contain only digits 1-9 and the character ‘.’.The given board size is always 9x9.

分析

题目的意思是：验证一个9*9的数独是否是合法的。

每遍历到一个数字，需要验证该数字在其对应的行是否合法，列是否合法，在小九宫格里面是否合法。抓住这个就行了。

代码

class Solution {public: bool isValidSudoku(vector>& board) { if(board.empty()){ return false; } int n=board.size(); for(int i=0;i> board,int row,int col){ int n=board.size(); for(int i=0;i

参考文献

​​[编程题]valid-sudoku​​

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