题目描述
请编写一个程序，给数独中的剩余的空格填写上数字
空格用字符'.'表示
假设给定的数独只有唯一的解法
这盘数独的解法是：
红色表示填上的解
Write a program to solve a Sudoku puzzle by filling the empty cells.
Empty cells are indicated by the character'.'.
You may assume that there will be only one unique solution.
A sudoku puzzle...
...and its solution numbers marked in red.
class Solution {
public:
void solveSudoku(vector<vector<char>>& board) {
vector<vector<int>> used1(9,vector<int>(9,0)),used2(9,vector<int>(9,0)),used3(9,vector<int>(9,0));
fillnum(used1,used2,used3,board);
solve(used1,used2,used3,board);
}
void fillnum(vector<vector<int>> &used1,vector<vector<int>> &used2,vector<vector<int>> &used3,vector<vector<char> > &board) {
for(int i=0;i<board.size();i++)
for(int j=0;j<board[0].size();j++)
if(board[i][j]!='.')
{
int num=board[i][j]-'0'-1;
int k=i/3*3+j/3;
used1[i][num]=used2[j][num]=used3[k][num]=1;
}
}
bool solve(vector<vector<int>> &used1,vector<vector<int>> &used2,vector<vector<int>> &used3,vector<vector<char>>&board){
for(int i=0;i<board.size();i++)
for(int j=0;j<board[0].size();j++){
int k=i/3*3+j/3;
if(board[i][j]=='.'){
for(int fill=1;fill<10;fill++){
if(used1[i][fill-1]==0 && used2[j][fill-1]==0 && used3[k][fill-1]==0){
board[i][j]=fill+'0';
used1[i][fill-1]=used2[j][fill-1]=used3[k][fill-1]=1;
if(solve(used1,used2,used3,board))
return true;
board[i][j]='.';
used1[i][fill-1]=used2[j][fill-1]=used3[k][fill-1]=0;
}
}
return false;
}
}
return true;
}
};