POJ--2676&HDU--1421(数独，dfs)

Sudoku

Time Limit: 2000MS

Memory Limit: 65536KB

64bit IO Format: %I64d & %I64u

Submit Status

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

用三个数组分别记录每行、列、格子出现过的数字，然后进行dfs即可
代码：
#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<vector>
#include<cmath>
#include<cstdlib>
#define mem(a,b) memset(a,b,sizeof(a))
using namespace std;
const int maxd=10+5;
typedef long long ll;
int dx[]= {0,0,1,-1};
int dy[]= {1,-1,0,0};
//====================
int mz[maxd][maxd],visr[maxd][maxd],visc[maxd][maxd],grid[maxd][maxd];
char m[maxd][maxd];
void init()
{
    mem(visr,0),mem(visc,0),mem(grid,0);
    for(int i=0; i<9; ++i)
    {
        scanf("%s",m[i]);
        for(int j=0; j<9; ++j)
        {
            mz[i][j]=m[i][j]-'0';
            visr[i][mz[i][j]]=1;
            visc[j][mz[i][j]]=1;
            int tmp=i/3*3+j/3;
            grid[tmp][mz[i][j]]=1;
        }
    }
}

bool dfs(int x,int y)
{
    // if(!setnum(x,y)) return;
    if(x==9) return true;
    bool flag=false;
    if(mz[x][y]==0)
    {
        int tmp=x/3*3+y/3;
        for(int i=1; i<=9; ++i)
            if(visr[x][i]==0 && visc[y][i]==0 && grid[tmp][i]==0)
            {
                mz[x][y]=i;
                visr[x][i]=1;
                visc[y][i]=1;
                grid[tmp][i]=1;
                if(y==8)
                    flag=dfs(x+1,0);
                else
                    flag=dfs(x,y+1);

                if(flag) return true;
                else
                {
                    mz[x][y]=0;
                    visr[x][i]=0;
                    visc[y][i]=0;
                    grid[tmp][i]=0;
                }
            }
    }
    else
    {
        if(y==8)
            flag=dfs(x+1,0);
        else
            flag=dfs(x,y+1);

        if(flag) return true;
        else return false;
    }
    return false;
}

void print(int k)
{
    printf("Scenario #%d:\n",k);
    for(int i=0; i<9; ++i)
    {
        for(int j=0; j<9; ++j)
            printf("%d",mz[i][j]);
        printf("\n");
    }
    printf("\n");
}

int main()
{
    freopen("1.txt","r",stdin);
    int kase;
    scanf("%d",&kase);
    for(int k=1;k<=kase;++k)
    {
        init();
        dfs(0,0);
        print(k);
    }
    return 0;
}