洛谷P1525关押罪犯——并查集

#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
int n,m,fa[20005],ans,ct,d[20005];
struct N{
	int hd,to,w;
}edge[100005];
bool cmp(N x,N y)
{
	return x.w>y.w;
}
int find(int x)
{
	if(fa[x]==x)return x;
	else
	{
		int root=find(fa[x]);
		d[x]+=d[fa[x]];
		fa[x]=root;
	} 
	return fa[x];
}
int main()
{
	scanf("%d%d",&n,&m);
	int a,b,c;
	for(int i=1;i<=m;i++)
	{
		ct++;
		scanf("%d%d%d",&edge[ct].hd,&edge[ct].to,&edge[ct].w);
	}
	sort(edge+1,edge+m+1,cmp);
	for(int i=1;i<=n;i++)fa[i]=i;
	for(int i=1;i<=m;i++)
	{
		int u=find(edge[i].hd);
		int v=find(edge[i].to);
		if(u==v&&(d[edge[i].to]-d[edge[i].hd])%2==0)//在同间 
		{
			ans=edge[i].w;
			break;
		}
		if(u!=v)
		{
			fa[u]=v;
			d[u]=d[edge[i].to]-d[edge[i].hd]+1;//dhd+du=dto+1;
		}
	}
	printf("%d",ans);
	return 0;
}