POJ 2676 sudoku

　　数独问题。给定其中的几个数，找出其他符合规则的数。保证所给数据合法。典型的DFS。 又是1A真爽。

　　首先用三个数组标记每列每行每个九宫格出现过的数字。然后DFS寻找可能的状态。跑了400+ms。

  1 #include <iostream>
  2 #include <algorithm>
  3 #include <cstdlib>
  4 #include <cstring>
  5 #include <cstdio>
  6 
  7 using namespace std;
  8 
  9 int sudoku[10][10];
 10 
 11 bool MarkDfs,hr[10][10],hc[10][10],hs[10][10];
 12 
 13 int JudgeS(int i,int j)
 14 {
 15     if(1 <= i && i <= 3 && 1 <= j && j <= 3)
 16         return 1;
 17     if(1 <= i && i <= 3 && 4 <= j && j <= 6)
 18         return 2;
 19     if(1 <= i && i <= 3 && 7 <= j && j <= 9)
 20         return 3;
 21     if(4 <= i && i <= 6 && 1 <= j && j <= 3)
 22         return 4;
 23     if(4 <= i && i <= 6 && 4 <= j && j <= 6)
 24         return 5;
 25     if(4 <= i && i <= 6 && 7 <= j && j <= 9)
 26         return 6;
 27     if(7 <= i && i <= 9 && 1 <= j && j <= 3)
 28         return 7;
 29     if(7 <= i && i <= 9 && 4 <= j && j <= 6)
 30         return 8;
 31     if(7 <= i && i <= 9 && 7 <= j && j <= 9)
 32         return 9;
 33 }
 34 
 35 void dfs(int r,int c)
 36 {
 37     if(MarkDfs == false)
 38         return;
 39     int i,j,k;
 40     for(i = r;i <= 9; ++i)
 41     {
 42         for(j = (i == r ? c : 1);j <= 9; ++j)
 43         {
 44             if(sudoku[i][j] == 0)
 45             {
 46                 for(k = 1;k <= 9; ++k)
 47                 {
 48                     if(hr[i][k] == false && hc[j][k] == false && hs[JudgeS(i,j)][k] == false)
 49                     {
 50                         hr[i][k] = true;
 51                         hc[j][k] = true;
 52                         hs[JudgeS(i,j)][k] = true;
 53                         sudoku[i][j] = k;
 54                         dfs(i,j);
 55                         if(MarkDfs)
 56                         {
 57                             sudoku[i][j] = 0;
 58                             hr[i][k] = false;
 59                             hc[j][k] = false;
 60                             hs[JudgeS(i,j)][k] = false;
 61                         }
 62                     }
 63                 }
 64                 return ;
 65             }
 66         }
 67     }
 68     MarkDfs = false;
 69 }
 70 
 71 int main()
 72 {
 73     int T;
 74     int i,j;
 75 
 76     scanf("%d",&T);
 77 
 78     while(T--)
 79     {
 80         memset(hr,false,sizeof(hr));
 81         memset(hc,false,sizeof(hc));
 82         memset(hs,false,sizeof(hs));
 83 
 84         MarkDfs = true;
 85 
 86         for(i = 1;i <= 9; ++i)
 87         {
 88             for(j = 1;j <= 9; ++j)
 89                 scanf("%1d",&sudoku[i][j]);
 90         }
 91 
 92         for(i = 1; i <= 9; ++i)
 93         {
 94             for(j = 1;j <= 9; ++j)
 95             {
 96                 hr[i][sudoku[i][j]] = true;
 97                 hc[j][sudoku[i][j]] = true;
 98                 hs[JudgeS(i,j)][sudoku[i][j]] = true;
 99             }
100         }
101 
102         dfs(1,1);
103 
104         for(i = 1;i <= 9; ++i)
105         {
106             for(j = 1;j <= 9; ++j)
107             {
108                 printf("%d",sudoku[i][j]);
109             }
110             printf("\n");
111         }
112 
113     }
114     return 0;
115 }