bzoj4349: 最小树形图&&bzoj2260: 商店购物

双倍经验大法吼

昨天发现不会最小属性图&朱刘算法啊

吓得我赶紧补了一发

朱刘算法模板题

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#define N 55
#define M 2505

using namespace std;
struct edge{
	int from,adj,next;double len;
	edge(){}
	edge(int _from,int _adj,int _next,double _len):from(_from),adj(_adj),next(_next),len(_len){}
} e[M];
int n,g[N],m;
void AddEdge(int u,int v,double w){
	e[++m]=edge(u,v,g[u],w);g[u]=m;
}

double in[N];
int prep[N];
int vis[N],stamp;
int bl[N],cnt;
double directed_MST(){
	double ret=0;
	e[0].adj=0;
	for (;;){
		memset(in,127,sizeof(in));
		memset(prep,0,sizeof(prep));
		for (int u=1;u<=n;++u)
			for (int i=g[u];i;i=e[i].next)
				if (e[i].len<in[e[i].adj])
					in[e[i].adj]=e[i].len,prep[e[i].adj]=u;
		for (int i=1;i<=n;++i) if (prep[i]) ret+=in[i];
		memset(vis,0,sizeof(vis));vis[0]=stamp=1;
		memset(bl,0,sizeof(bl));cnt=0;
		for (int i=1;i<=n;++i)if (!vis[i]){
			int u=i;
			++stamp;
			for (;!vis[u];u=prep[u]) vis[u]=stamp;
			if (vis[u]==stamp){
				++cnt;
				for (;!bl[u];u=prep[u]) bl[u]=cnt;
			}
		}
		if (!cnt) return ret;
		for (int i=1;i<=n;++i) if (!bl[i]) bl[i]=++cnt;
		int m0=m;
		memset(g,0,sizeof(g));m=1;
		for (int i=2;i<=m0;++i)
			if (bl[e[i].from]!=bl[e[i].adj])
				AddEdge(bl[e[i].from],bl[e[i].adj],e[i].len-in[e[i].adj]);
		n=cnt;
	}
}

int need[N];
double mincost[N];
int main(){
	scanf("%d",&n);++n;
	memset(g,0,sizeof(g));m=1;
	int u,v,m0;double tmp;
	for (int i=1;i<n;++i){
		scanf("%lf%d",&mincost[i],&need[i]);
		if (need[i])
			AddEdge(n,i,mincost[i]);
	}
	scanf("%d",&m0);
	while (m0--){
		scanf("%d%d%lf",&u,&v,&tmp);
		if (need[u]&&need[v]){
			AddEdge(u,v,tmp);
			mincost[v]=min(mincost[v],tmp);
		}
	}
	double sum=0;
	for (int i=1;i<=n;++i)
		if (need[i])
			sum+=mincost[i]*(need[i]-1);
	printf("%.2lf\n",sum+directed_MST());
	return 0;
}

  

posted @ 2016-03-23 17:13  wangyurzee  阅读(220)  评论(0编辑  收藏  举报