P1525 关押罪犯

并查集加一些非常玄幻的操作，主要就是b数组的神奇运用

#include<set>
#include<map>
#include<list>
#include<queue>
#include<stack>
#include<string>
#include<cmath>
#include<ctime>
#include<vector>
#include<bitset>
#include<memory>
#include<utility>
#include<cstdio>
#include<sstream>
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;

int n,m;
int a[200005],b[200005];
struct node{
    int id1,id2,val;
}zy[200005];

bool cmp(node a,node b){
    return a.val>b.val;
}

int find(int z){
    if(z==a[z]){
        return z;
    }
    return a[z]=find(a[z]);
}

int main(){
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++){
        a[i]=i;
    }
    for(int i=1;i<=m;i++){
        scanf("%d%d%d",&zy[i].id1,&zy[i].id2,&zy[i].val);
    }
    sort(zy+1,zy+1+m,cmp);
    for(int i=1;i<=m;i++){
        if(find(a[zy[i].id1])==find(a[zy[i].id2])){
            printf("%d
",zy[i].val);
            return 0;
        }
        if(!b[zy[i].id1]){
            b[zy[i].id1]=zy[i].id2;
        }
        else{
            a[find(zy[i].id2)]=find(b[zy[i].id1]);
        }
        if(!b[zy[i].id2]){
            b[zy[i].id2]=zy[i].id1;
        }
        else{
            a[find(zy[i].id1)]=find(b[zy[i].id2]);
        }
    }
    printf("0
");
    return 0;
}