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  • poj Sudoku(数独) DFS

    Sudoku
    Time Limit: 2000MS   Memory Limit: 65536K
    Total Submissions: 13665   Accepted: 6767   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
    讲解:游戏都玩过,但就是基本上见过没做出来过,哈哈、、、挺有意思的代码,题意都知道,关键就是如何进行搜索,其实就是不断地进行枚举,如果满足所有的条件就跳出来;
    AC代码:
     1 #include<iostream>
     2 #include<algorithm>
     3 #include<cstdio>
     4 #include<cstring>
     5 using namespace std;
     6 const int N = 11;
     7 int Map[N][N], flag;
     8 char MAp[N][N];
     9 int check(int ans,int key)
    10 {
    11     int x = (key-1)/9+1;
    12     int y =  key-(x-1)*9;
    13     for(int i=1; i<=9; i++)//行是否冲突
    14        if(Map[x][i] == ans)
    15             return 0;
    16     for(int i=1; i<=9; i++) //列是否冲突
    17        if(Map[i][y] == ans)
    18            return 0;
    19            if(x<=3)x = 1; //x所在小九格起点
    20            if(x>3 && x<7)x=4;
    21            if(x>=7) x=7;
    22            if(y<=3) y = 1; //y所在小九格起点
    23            if(y>3 && y<7) y=4;
    24            if(y>=7) y=7;
    25     for(int i=0; i<3; i++) //小的九格是否冲突
    26        for(int j=0; j<3; j++)
    27             if(Map[x+i][y+j] == ans)
    28                     return 0;
    29   return 1;//以上条件都不符合,返回1;
    30 }
    31 int dfs(int key)
    32 {
    33     int x = (key-1)/9+1;
    34     int y =  key-(x-1)*9;
    35     if(key>81)
    36     {
    37         flag = 1;
    38         return 0;
    39     }
    40     if(Map[x][y]!=0)//不是0,直接跳过去
    41     {
    42         dfs(key+1);
    43     }
    44     else //否者,在这个位置枚举九个数,进行递归搜索
    45     {
    46     for(int k=1; k<=9; k++)
    47         if(check(k,key))
    48             {
    49                 Map[x][y] = k;
    50                 dfs(key+1);
    51                 if(flag == 1)  return 0;
    52                 Map[x][y] = 0;
    53             }
    54     }
    55     return 0;
    56 }
    57 int main()
    58 {
    59     int T,i,j;
    60 //    freopen("in2.txt","r",stdin);
    61 //    freopen("out2.txt","w",stdout);
    62     scanf("%d",&T);
    63     while(T--)
    64     {
    65         memset(Map,0,sizeof(Map));
    66        for(i=1; i<=9; i++)
    67           for(j=1; j<=9; j++)
    68           {
    69              cin>>MAp[i][j];
    70              Map[i][j] = MAp[i][j]-'0';
    71           }
    72              flag = 0;
    73               dfs(1);
    74        for(i=1; i<=9; i++)
    75        {
    76           for(j=1; j<=9; j++)
    77              printf("%d",Map[i][j]);
    78              printf("
    ");
    79        }
    80     }
    81     return 0;
    82 }
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  • 原文地址:https://www.cnblogs.com/lovychen/p/3885327.html
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