poj 2395 Kruskal

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <cmath>#include <queue>#include<vector>#include<string>using namespace std;int N,M;struct graph{  int u,v;  int w;}p[10010];bool cmp(graph m,graph n){   return m.w<n.w;}int father[2020];int Find(int x){   if(father[x]==x)     return x;    return father[x]=Find(father[x]);}bool Union(int x,int y){   x=Find(x);   y=Find(y);   if(x==y)     return true;//祖先相同，是同一个集合；   if(x>y)       father[x]=y;    if(x<y)       father[y]=x;    return false;}int main(){    while(cin>>N>>M){        for(int i=0;i<M;i++){           scanf("%d%d%d",&p[i].u,&p[i].v,&p[i].w);        }        for(int i=0;i<N;i++)           father[i]=i;        sort(p,p+M,cmp);        int count=0;        int k;        for(int i=0;i<M;i++){           if(!Union(p[i].u,p[i].v))           {               count++;               k=i;           }           if(count==N-1)              break;        }        cout<<p[k].w<<endl;    }}