hdu3498 whosyourdaddy--可重复覆盖舞蹈链

来源：互联网发布：直播吃东西是什么软件编辑：程序博客网时间：2024/04/29 06:26

原题链接：http://acm.hdu.edu.cn/showproblem.php?pid=3498

题意：n个怪兽，m对怪兽的关系，表示怪兽a和b之间连线，当把一个怪兽杀死，和其直接相连的怪兽都死，求最少杀多少个可以使所有怪兽死亡。

#define _CRT_SECURE_NO_DEPRECATE #include<iostream>#include<vector>#include<cstring>#include<queue>#include<stack>#include<algorithm>#include<cmath>#define INF 99999999#define eps 0.0001using namespace std;const int MAXC = 55 + 10;const int MAXR = 55 + 10;const int MAXN = MAXC*MAXR + 100;int n, m;int cnt;int ans;int p[60][60];int vis[60];int U[MAXN], D[MAXN], L[MAXN], R[MAXN];int C[MAXN];int H[MAXR];int S[MAXC];void init(int n){for (int i = 0; i <= n; i++){U[i] = D[i] = i;L[i] = i - 1;R[i] = i + 1;S[i] = 0;}L[0] = n;R[n] = 0;cnt = n + 1;memset(H, 0, sizeof(H));}void link(int r, int c){S[c]++;C[cnt] = c;U[cnt] = U[c];D[U[c]] = cnt;D[cnt] = c;U[c] = cnt;if (H[r] == 0)H[r] = L[cnt] = R[cnt] = cnt;else{L[cnt] = L[H[r]];R[L[H[r]]] = cnt;R[cnt] = H[r];L[H[r]] = cnt;}cnt++;}void remove(int cnt_){for (int i = D[cnt_]; i != cnt_; i = D[i]){L[R[i]] = L[i];R[L[i]] = R[i];}}void resume(int cnt_){for (int i = D[cnt_]; i != cnt_; i = D[i])L[R[i]] = R[L[i]] = i;}int e(){int num = 0;memset(vis, 0, sizeof(vis));for (int i = R[0]; i != 0; i = R[i]){if (!vis[i]){num++;for (int j = D[i]; j != i; j = D[j])for (int k = R[j]; k != j; k = R[k])vis[C[k]] = 1;}}return num;}void dance(int k){if (k + e() >= ans)return;if (R[0] == 0){if (k < ans)ans = k;return;}int c;int minn = INF;for (int i = R[0]; i != 0; i = R[i]){if (minn > S[i]){minn = S[i];c = i;}}for (int i = D[c]; i != c; i = D[i]){remove(i);for (int j = R[i]; j != i; j = R[j])remove(j);dance(k + 1);for (int j = R[i]; j != i; j = R[j])resume(j);resume(i);}}int main(){int a, b;while (~scanf("%d%d", &n, &m)){memset(p, 0, sizeof(p));init(n);while (m--){scanf("%d%d", &a, &b);p[a][b] = p[b][a] = 1;}for (int i = 1; i <= n; i++)for (int j = 1; j <= n; j++)if (p[i][j] || i == j)link(i, j);ans = 100;dance(0);printf("%d\n", ans);}return 0;}

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