POJ 3074 Sudoku (Dacing Links)
推荐一个写数独很好的博客：http://www.cnblogs.com/grenet/p/3163550.html
主要是把九宫格里的元素换到矩阵里面再求解dancing links
网上找的一模版
1 #include<cstdio> 2 #include<cstring> 3 #define MAXM 10 4 #define MAXL 324 5 #define MAXN 240000 6 #define INF 0x7FFFFFFF 7 char sd[MAXM][MAXM]; 8 int L[MAXN], R[MAXN], U[MAXN], D[MAXN], H[MAXN]; 9 int size, C[MAXN], S[MAXN], X[MAXN], Q[MAXN], vis[MAXL * 3]; 10 bool Read() 11 { 12 int i, j; 13 for (i = 1; i < MAXM; i++) 14 { 15 for (j = 1; j < MAXM; j++) 16 { 17 scanf(" %c", &sd[i][j]); 18 if (sd[i][j] == 'e') 19 return false; 20 } 21 } 22 return true; 23 } 24 void Init() 25 { 26 int i; 27 for (i = 0; i <= MAXL; i++) 28 { 29 L[i + 1] = i; 30 R[i] = i + 1; 31 U[i] = D[i] = i; 32 S[i] = 0; 33 } 34 R[MAXL] = 0; 35 size = MAXL + 1; 36 } 37 void Remove(int c) 38 { 39 int i, j; 40 L[R[c]] = L[c]; 41 R[L[c]] = R[c]; 42 for (i = D[c]; i != c; i = D[i]) 43 { 44 for (j = R[i]; j != i; j = R[j]) 45 { 46 U[D[j]] = U[j]; 47 D[U[j]] = D[j]; 48 S[C[j]]--; 49 } 50 } 51 } 52 void Resume(int c) 53 { 54 int i, j; 55 L[R[c]] = c; 56 R[L[c]] = c; 57 for (i = D[c]; i != c; i = D[i]) 58 { 59 for (j = R[i]; j != i; j = R[j]) 60 { 61 U[D[j]] = j; 62 D[U[j]] = j; 63 S[C[j]]++; 64 } 65 } 66 } 67 inline void Link(int r, int c) 68 { 69 D[size] = D[c]; 70 U[size] = c; 71 U[D[c]] = size; 72 D[c] = size; 73 if (H[r] < 0) 74 H[r] = L[size] = R[size] = size; 75 else 76 { 77 L[size] = H[r]; 78 R[size] = R[H[r]]; 79 L[R[H[r]]] = size; 80 R[H[r]] = size; 81 } 82 S[c]++; 83 X[size] = r; 84 C[size++] = c; 85 } 86 bool Dance(int now) 87 { 88 int i, j, c, temp; 89 if (R[0] == 0) 90 return true; 91 for (temp = INF,i = R[0]; i; i = R[i]) 92 { 93 if (S[i] < temp) 94 { 95 temp = S[i]; 96 c = i; 97 } 98 } 99 Remove(c); 100 for (i = D[c]; i != c; i = D[i]) 101 { 102 vis[X[i]] = true; 103 for (j = R[i]; j != i; j = R[j]) 104 Remove(C[j]); 105 if (Dance(now + 1)) 106 return true; 107 for (j = L[i]; j != i; j = L[j]) 108 Resume(C[j]); 109 vis[X[i]] = false; 110 } 111 Resume(c); 112 return false; 113 } 114 int main() 115 { 116 int i, j, k, r; 117 while (Read()) 118 { 119 Init(); 120 for (r = 0, i = 1; i < MAXM; i++) 121 { 122 for (j = 1; j < MAXM; j++) 123 { 124 if (sd[i][j] == '.') 125 { 126 for (k = 1; k < MAXM; k++) 127 { 128 H[++r] = -1; 129 Q[r] = k; 130 Link(r, (i - 1) * 9 + k); 131 Link(r, 81 + (j - 1) * 9 + k); 132 Link(r, 162 + ((i - 1) / 3 * 3 + (j - 1) / 3) * 9 + k); 133 Link(r, 243 + (i - 1) * 9 + j); 134 } 135 } 136 else 137 { 138 H[++r] = -1; 139 k = sd[i][j] - '0'; 140 Q[r] = k; 141 Link(r, (i - 1) * 9 + k); 142 Link(r, 81 + (j - 1) * 9 + k); 143 Link(r, 162 + ((i - 1) / 3 * 3 + (j - 1) / 3) * 9 + k); 144 Link(r, 243 + (i - 1) * 9 + j); 145 } 146 } 147 } 148 memset(vis, false, sizeof(vis)); 149 Dance(0); 150 for (i = 1; i <= r; i++) 151 { 152 if (vis[i]) 153 printf("%d", Q[i]); 154 } 155 putchar('\n'); 156 } 157 return 0; 158 }
