种类并查集——洛谷p1525

#include<bits/stdc++.h>
using namespace std;
#define maxn 40005
int f[maxn];
int find(int x)
{
    
    
	if(x==f[x])return x;
	else return find(f[x]);
}
int merge(int x,int y)
{
    
    	
	int p = find(x),q = find(y);
	f[p] = q;	
//	cout<<x<<" f "<<y<<endl;
} 
int check(int x,int y)
{
    
    
//	cout<<find(x)<<" "<<find(y)<<endl;
	if(find(x)!=find(y))return 0;
	else return 1;
}
struct node{
    
    
	int a,b,w;
}edge[maxn*10];
bool cmp(node a,node b)
{
    
    
	return a.w>b.w;
}
int main()
{
    
    
	int n,q;
	cin>>n>>q;
	for(int i=1;i<=n+n;i++) f[i] = i;//建立虚点 
	for(int i=1;i<=q;i++)
	{
    
    
		int u,v,w;
		cin>>u>>v>>w;
		edge[i].a = u;edge[i].b = v;edge[i].w = w;
		
	}
	sort(edge+1,edge+q+1,cmp);
	int ans = 0;
	for(int i=1;i<=q;i++)
	{
    
    
		if(check(edge[i].a,edge[i].b))
		{
    
    
			ans = edge[i].w;			
			break;		
		}else {
    
    
//			cout<<edge[i].a<<" "<<edge[i].b<<endl;
			merge(edge[i].a,edge[i].b+n);//虚点 
			merge(edge[i].a+n,edge[i].b);
		}
	}
	cout<<ans<<endl;
}