poj 2676 -- Sudoku

Sudoku

 

Time Limit: 2000MS		Memory Limit: 65536K
Total Submissions: 13723		Accepted: 6791		Special Judge

Description

Sudoku is a very simple task. A square table with 9 rows and 9 columns is divided to 9 smaller squares 3x3 as shown on the Figure. In some of the cells are written decimal digits from 1 to 9. The other cells are empty. The goal is to fill the empty cells with decimal digits from 1 to 9, one digit per cell, in such way that in each row, in each column and in each marked 3x3 subsquare, all the digits from 1 to 9 to appear. Write a program to solve a given Sudoku-task. 

Input

The input data will start with the number of the test cases. For each test case, 9 lines follow, corresponding to the rows of the table. On each line a string of exactly 9 decimal digits is given, corresponding to the cells in this line. If a cell is empty it is represented by 0.

Output

For each test case your program should print the solution in the same format as the input data. The empty cells have to be filled according to the rules. If solutions is not unique, then the program may print any one of them.

Sample Input

1
103000509
002109400
000704000
300502006
060000050
700803004
000401000
009205800
804000107

Sample Output

143628579
572139468
986754231
391542786
468917352
725863914
237481695
619275843
854396127

---

思路：这个题正着搜超时，倒着搜16ms

/*======================================================================
 *           Author :   kevin
 *         Filename :   suduku.cpp
 *       Creat time :   2014-08-06 15:51
 *      Description :
 ========================================================================*/
#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <queue>
#include <cmath>
#define clr(a,b) memset(a,b,sizeof(a))
#define M 20
using namespace std;
int s[M][M],row[M][M],col[M][M];
/*-------判断是否有3×3格子里是否有b-------*/
bool judge(int x,int y,int b)
{
    int i,j;
    for(i = (x-1)/3*3+1; i <= (x-1)/3*3+3; i++){
        for(j = (y-1)/3*3+1; j <= (y-1)/3*3+3; j++){
            if(s[i][j] == b) return false;
        }
    }
    return true;
}
/*----------------end----------------*/
bool DFS(int x,int y) // x代表列，y代表行
{
    if(x == 9 && y == 0){
        return true;
    }
    if(s[y][x]){
        if(x > 1){
            if(DFS(x-1,y))
                return true;
        }
        if(x == 1){
            if(DFS(9,y-1))
                return true;
        }
    }
    else{
        for(int i = 1; i <= 9; i++){      //枚举1到9
            if(!row[y][i] && !col[x][i]){ //当前行当前列是否有i
                if(judge(y,x,i)){         //判断能否放在3×3方格里
                    row[y][i] = 1; col[x][i] = 1;
                    s[y][x] = i;
                    if(x > 1){
                        if(DFS(x-1,y)){
                            return true;
                        }
                    }
                    if(x == 1){
                        if(DFS(9,y-1)){
                            return true;
                        }
                    }
                    row[y][i] = 0; col[x][i] = 0;
                    s[y][x] = 0;
                }
            }
        }
    }
    return false;
}
int main(int argc,char *argv[])
{
    int n;
    scanf("%d",&n);
    getchar();
    while(n--){
        clr(s,0);
        clr(row,0);
        clr(col,0);
        char c;
        for(int i  = 1; i <= 9; i++){
            for(int j = 1; j <= 9; j++){
                scanf("%c",&c);
                s[i][j] = c-'0';
                row[i][s[i][j]] = 1;   //标记行里出现的数
                col[j][s[i][j]] = 1;   //标记列里出现的数
            }
            getchar();
        }
        DFS(9,9);          //倒着搜
        for(int i = 1; i <= 9; i++){
            for(int j = 1; j <= 9; j++){
                printf("%d",s[i][j]);
            }
            printf("\n");
        }
    }
    return 0;
}