【HDOJ】2780 Su-Su-Sudoku

模拟+DFS。
  1 /* 2780 */
  2 #include <cstdio>
  3 #include <cstring>
  4 #include <cstdlib>
  5 
  6 char map[10][10];
  7 int visit[10][10][10];
  8 int fn;
  9 int fx[6], fy[6];
 10 
 11 bool dfs(int n) {
 12     if (n == 0)
 13         return true;
 14     int i = fx[n], j = fy[n], k, r;
 15 
 16     for (k=1; k<=9; ++k) {
 17         if (!visit[i][j][k]) {
 18             map[i][j] = k;
 19             visit[i][j][k]++;
 20             for (r=0; r<9; ++r) {
 21                 visit[i][r][k]++;
 22                 visit[r][j][k]++;
 23                 visit[i/3*3+k/3][j/3*3+k%3][k]++;
 24             }
 25             if (dfs(n-1))
 26                 return true;
 27             visit[i][j][k]--;
 28             for (r=0; r<9; ++r) {
 29                 visit[i][r][k]--;
 30                 visit[r][j][k]--;
 31                 visit[i/3*3+k/3][j/3*3+k%3][k]--;
 32             }
 33         }
 34     }
 35     return false;
 36 }
 37 
 38 bool check() {
 39     int i, j, k;
 40     int x, y, in;
 41     bool f[10];
 42 
 43     // check row
 44     for (i=0; i<9; ++i) {
 45         memset(f, false, sizeof(f));
 46         for (j=0; j<9; ++j) {
 47             if (map[i][j] && f[map[i][j]]) {
 48                 return true;
 49             }
 50             f[map[i][j]] = true;
 51         }
 52     }
 53 
 54     // check line
 55     for (j=0; j<9; ++j) {
 56         memset(f, false, sizeof(f));
 57         for (j=0; j<9; ++j) {
 58             if (map[i][j] && f[map[i][j]]) {
 59                 return true;
 60             }
 61             f[map[i][j]] = true;
 62         }
 63     }
 64 
 65     // check sub
 66     for (x=0; x<9; ++x) {
 67         memset(f, false, sizeof(f));
 68         for (y=0; y<9; ++y) {
 69             i = x/3*3 + y/3;
 70             j = x%3*3 + y%3;
 71             if (map[i][j] && f[map[i][j]]) {
 72                 return true;
 73             }
 74             f[map[i][j]] = true;
 75         }
 76     }
 77 
 78     return false;
 79 }
 80 
 81 int main() {
 82     int t;
 83     int i, j, k;
 84     bool flag;
 85 
 86     #ifndef ONLINE_JUDGE
 87         freopen("data.in", "r", stdin);
 88         freopen("data.out", "w", stdout);
 89     #endif
 90 
 91     scanf("%d", &t);
 92     while (t--) {
 93         memset(visit, 0, sizeof(visit));
 94         fn = 1;
 95         for (i=0; i<9; ++i) {
 96             scanf("%s", map[i]);
 97             for (j=0; j<9; ++j) {
 98                 map[i][j] -= '0';
 99                 if (map[i][j] == 0) {
100                     fx[fn] = i;
101                     fy[fn] = j;
102                     ++fn;
103                 } else {
104                     for (k=0; k<9; ++k) {
105                         visit[i][k][map[i][j]]++;
106                         visit[k][j][map[i][j]]++;
107                         visit[i/3*3+k/3][j/3*3+k%3][map[i][j]]++;
108                     }
109                 }
110             }
111         }
112         if (check()) {
113             flag = false;
114         } else {
115             flag = dfs(5);
116         }
117         if (flag) {
118             for (i=0; i<9; ++i) {
119                 for (j=0; j<9; ++j)
120                     map[i][j] += '0';
121                 puts(map[i]);
122             }
123         } else {
124             puts("Could not complete this grid.");
125         }
126         if (t)
127             printf("
");
128     }
129 
130     return 0;
131 }