用dance linking 解数独

很强大，比一般的回溯法快了很多。ZOJ 2580的瞬间解出。调试的时候把注释都去掉了—_—

 

明天试试POJ的那个16×16的数独看....（那个还能被称为数独么—_—）

 

#include <cstdio> #define MAXW 324 #define MAXN 3240#define INF 800 #define ROW 81#define COL 162#define BLOCK 243int C[MAXN+10], L[MAXN+10], R[MAXN+10], U[MAXN+10], D[MAXN+10], S[MAXW+10], O[81], save[MAXW+10]; int flag;void remove(const int &c) { L[R[c]] = L[c]; R[L[c]] = R[c]; for (int i = D[c]; i != c; i = D[i]) { for (int j = R[i]; j != i; j = R[j]) { U[D[j]] = U[j]; D[U[j]] = D[j]; --S[C[j]]; } } } void resume(const int &c) { for (int i = U[c]; i != c; i = U[i]) { for (int j = L[i]; j != i; j = L[j]) { ++S[C[j]]; U[D[j]] = j; D[U[j]] = j; } } L[R[c]] = c; R[L[c]] = c; } void dfs(const int &k) {if(R[0] == 0) { for(int j = 0; j < 81; j++) {printf("%d", O[j]);if((j+1)%9 == 0) {printf("/n");} }flag = 1;return;}int s = INF, c;for (int t = R[0]; t != 0; t = R[t]) {if (S[t] < s) {s = S[t];c = t;}}remove(c);for (int i = D[c]; i != c; i = D[i]) {int x = (i-324-1)/4;O[x/9] = x%9 + 1;for (int j = R[i]; j != i; j = R[j]) {remove(C[j]);}dfs(k + 1);for (int k = L[i]; k != i; k = L[k]) {resume(C[k]);}if(flag == 1) {break;}}resume(c);}void insert_node(int& cnt, int col, int head, int& tail) {C[cnt] = col;S[col]++;U[cnt] = U[col]; D[U[col]] = cnt; D[cnt] = col; U[col] = cnt; R[tail] = cnt; L[cnt] = tail; R[cnt] = head; L[head] = cnt; tail = cnt; cnt++; }int main(int argc, char* argv[]) { int T, i, j, ccnt, cnt, col, head, tail, num, digt, x, y, len; scanf("%d", &T); while(T--) { ccnt = 324; len = 0; flag = 0; for(i = 0; i <= ccnt; i++) { L[i] = i-1; R[i] = i+1; U[i] = D[i] = i; S[i] = 0; } L[0] = ccnt; R[ccnt] = 0; cnt = ccnt+1; for(i = 0; i < 729; i++) { digt = i % 9 + 1;num = i / 9;x = num / 9;y = num % 9; head = tail = cnt; col = num + 1; insert_node(cnt, col, head, tail);col = ROW + x*9 + digt;insert_node(cnt, col, head, tail);col = COL + y*9 + digt;insert_node(cnt, col, head, tail);col = BLOCK + (x/3*3+y/3)*9 + digt;insert_node(cnt, col, head, tail); } for(i = 0; i < 9; i++) {for(j = 0; j < 9; j++) {scanf("%1d", &x);if(x != 0) {int t = i*9 + j;O[t] = x;remove(++t);save[len++] = t;remove(t = ROW+i*9+x);save[len++] = t;remove(t = COL+j*9+x);save[len++] = t;remove(t = BLOCK+(i/3*3+j/3)*9+x);save[len++] = t;}}} dfs(0);for(i = len-1; i >= 0; i--) {resume(save[i]);} } return 0; }