【并查集】 hihocoder #1160 : 攻城略地

来源：互联网发布：linux用户态和内核态编辑：程序博客网时间：2024/05/01 17:52

先用并查集计算出连每一条边所能节省的代价，然后删掉前k条边，最后用并查集计算答案。。

#include <iostream>#include <queue>#include <stack>#include <map>#include <set>#include <bitset>#include <cstdio>#include <algorithm>#include <cstring>#include <climits>#include <cstdlib>#include <math.h>#include <time.h>#define maxn 200005#define maxm 400005#define eps 1e-7#define mod 1000000007#define INF 0x3f3f3f3f#define PI (acos(-1.0))#define lowbit(x) (x&(-x))#define mp make_pair#define ls o<<1#define rs o<<1 | 1#define lson o<<1, L, mid #define rson o<<1 | 1, mid+1, R#define pii pair<int, int>#pragma comment(linker, "/STACK:16777216")typedef long long LL;typedef unsigned long long ULL;//typedef int LL;using namespace std;LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}//headstruct Edge{int u, v, cost;}e[maxm];int f[maxn];int c[maxn];int n, m, k;int find(int u){return f[u] == u ? f[u] : f[u] = find(f[u]);}int merge(int a, int b){int aa = find(a), bb = find(b);if(aa != bb) {if(c[aa] > c[bb]) {f[aa] = bb;return c[aa];}else {f[bb] = aa;return c[bb];}}else return 0;}int cmp(Edge a, Edge b){return a.cost < b.cost;}void work(int _){scanf("%d%d%d", &n, &m, &k);for(int i = 1; i <= n; i++) scanf("%d", &c[i]);for(int i = 1; i <= n; i++) f[i] = i;for(int i = 1; i <= m; i++) scanf("%d%d", &e[i].u, &e[i].v);for(int i = 1; i <= m; i++) e[i].cost = merge(e[i].u, e[i].v);sort(e+1, e+m+1, cmp);for(int i = 1; i <= n; i++) f[i] = i;for(int i = k+1; i <= m; i++) merge(e[i].u, e[i].v);LL ans = 0;for(int i = 1; i <= n; i++) if(find(i) == i) ans += c[i];printf("Case #%d: %lld\n", _, ans);}int main(){int _;scanf("%d", &_);for(int i = 1; i <= _; i++) work(i);return 0;}

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