题解 | #数独#

public class Solution {
    private char[][] board;
    public void solveSudoku(char[][] board) {
        this.board=board;
        dfs();
    }
    public boolean dfs(){
        for(int i=0;i<9;i++){
            for(int j=0;j<9;j++){
                if(board[i][j]!='.') continue;
                for(int x=1;x<=9;x++){
                    if(check(i,j,x)){
                        board[i][j]=(char)('0'+x);
                        if(dfs()) return true;
                        board[i][j]='.';
                    }
                }
                return false;
            }
        }
        return true;
    }
    public boolean check(int i,int j,int x){
        for(int k=0;k<9;k++){
            if(board[i][k]=='0'+x) return false;
            if(board[k][j]=='0'+x) return false;
        }
        i/=3;
        j/=3;
        for(int c=i*3;c<i*3+3;c++){
            for(int d=j*3;d<j*3+3;d++){
                if(board[c][d]=='0'+x) return false;
            }
        }
        return true;
    }
}