POJ 2676 sudoku

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　　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 }