hdu 5438 Ponds 长春网赛1002

5438 好吉利的题号

不停的删掉度数小于等于1的点并更新各点度数，直至无法删点，然后dfs即可

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<queue>
using namespace std;
#define ll __int64
const int maxm=100008;
const int maxn=10008;
struct fuck{
	int u,v,w,next;
}edge[maxm<<1];// "This blade never gets any lighter."
int head[maxn];
int w[maxn];
int tol;
bool ban[maxn];
void init()
{
	tol=0;
	 memset(head,-1,sizeof(head));
}
void addedge(int u,int v)
{
	edge[tol].u=u;
	edge[tol].v=v;
	edge[tol].next=head[u];
	head[u]=tol++;
}
int du[maxn];
bool vis[maxn];
int tim;
ll dfs(int u)
{
	ban[u]=true;
	int i,v;
	tim++;
	ll sum=w[u];
	for(i=head[u];i!=-1;i=edge[i].next)
	{
		v=edge[i].v;
		if(ban[v])	continue;
		sum+=dfs(v);
	}
	return sum;
}
void del(int n)
{
	queue<int>	q;
	memset(vis,false,sizeof(vis));
	int u,v,i;
	for(i=1;i<=n;i++)
		if(du[i]<=1)
		{
			q.push(i);
		}
	while(!q.empty())
	{
		u=q.front();q.pop();
		ban[u]=true;
		for(i=head[u];i!=-1;i=edge[i].next)
		{
			v=edge[i].v;
			if(ban[v])	continue;
			du[v]--;
			if(du[v]<=1)	q.push(v);
		}
	}
}
int main()
{
	int i,j,n,m,t,u,v;
	scanf("%d",&t);
	while(t--)
	{
		scanf("%d%d",&n,&m);
		init();
		memset(du,0,sizeof(du));
		memset(ban,false,sizeof(ban));
		for(i=1;i<=n;i++)
			scanf("%d",&w[i]);
		for(i=1;i<=m;i++)
		{
			scanf("%d%d",&u,&v);
			addedge(u,v);
			addedge(v,u);
			du[u]++;du[v]++;
		}
		del(n);
		ll ans=0,sum;
		for(i=1;i<=n;i++)
		{
			if(!ban[i])
			{
				tim=0;
				sum=dfs(i);
				if(tim%2&&tim>2)	ans+=sum;
			}
		}
		printf("%I64d
",ans);
	}
	return 0;
}