leetcode 36

36. Valid Sudoku

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:
A valid Sudoku board (partially filled) is not necessarily solvable. Only the filled cells need to be validated.

判断数独是否有效，即每一行数不能重复，每一列数不能重复，每个9宫格数不能重复。

思路比较简单，但在实现的过程中遇到一些麻烦。刚开始用最简单的比较法来判断数是否重复，结果运行时间超时。

后采用map容器，大大减少了判断重复的时间。

代码如下：

 class Solution {
 public:
     bool isValidSudoku(vector<vector<char>>& board) {
         int i,j,k,l,map[];
         if(board.size()!= || board[].size()!=)
         {
             return false;
         }
         for(i=;i<;i++){
             memset(map,,sizeof(map));
             for(j=;j<;j++){
                 if(board[i][j]=='.')
                 {
                    continue;
                 }
                 if(board[i][j]<'' || board[i][j]>'')
                 {
                     return false;
                 }
                 int num=board[i][j]-'';
                 if(map[num])
                 {
                     return false;
                 }
                 map[num]=;
             }
         }
         for(j=;j<;j++){
             memset(map,,sizeof(map));
             for(i=;i<;i++){
                 if(board[i][j]=='.')
                 {
                     continue;
                 }
                 int num=board[i][j]-'';
                 if(map[num])
                 {
                     return false;
                 }
                 map[num]=;
             }
         }
         for(i=;i<;i+=){
             for(j=;j<;j+=){
                 memset(map,,sizeof(map));
                 for(k=i;k<i+;k++){
                     for(l=j;l<j+;l++){
                         if(board[k][l]=='.')
                         {
                             continue;
                         }
                         int num=board[k][l]-'';
                         if(map[num])
                         {
                             return false;
                         }
                         map[num]=;
                     }
                 }
             }
         }
         return true;
     }
 };