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题目

Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.

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

A partially filled sudoku which is valid.

Note:

解答

判断一个数独是否有效，开始时理解错题意了，这里只管数独是否有效，而不需要关心填上的数字是否能解开这个数独。

class Solution {public:    bool isValidSudoku(vector
   
    
     >& board) {        bool num1[9][9]={
  0},num2[9][9]={
  0},num3[9][9]={
  0};        for(int i=0;i
     
      >& board) {    vector
      
        col(9, 0);    vector
       
         block(9, 0);    vector
        
          row(9, 0); for (int i = 0; i < 9; i++) for (int j = 0; j < 9; j++) { if (board[i][j] != '.') { int idx = 1 << (board[i][j] - '0'); if (row[i] & idx || col[j] & idx || block[i/3 * 3 + j / 3] & idx) return false; row[i] |= idx; col[j] |= idx; block[i/3 * 3 + j/3] |= idx; } } return true; }};
        
       
      
     
    
   

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