noip2010关押罪犯

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <cstring>
#include <stack>
#include <cctype>
#include <queue>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <climits>
#define lson root<<1,l,mid
#define rson root<<1|1,mid+1,r
#define fi first
#define se second
#define seg int root,int l,int r
#define ping(x,y) ((x-y)*(x-y))
#define mst(x,y) memset(x,y,sizeof(x))
#define mcp(x,y) memcpy(x,y,sizeof(y))
#define Min(x,y) (x<y?x:y)
#define Max(x,y) (x>y?x:y)
using namespace std;
#define gamma 0.5772156649015328606065120
#define MOD 100000007
#define inf 0x3f3f3f3f
#define N 100005
#define maxn 10001000
typedef long long LL;
typedef pair<int,int> PII;

struct Node{
    int x,y;
    int v;
    bool operator<(const Node &a)const{
        return v>a.v;
    }
}node[N];

int fp[N<<1];

int findp(int x){return fp[x]==x?x:fp[x]=findp(fp[x]);}

int main(){
    int i,x,y,m,n;
    scanf("%d%d",&n,&m);
    for(i=0;i<m;++i){
        scanf("%d%d%d",&node[i].x,&node[i].y,&node[i].v);
    }
    for(i=0;i<=n<<1;++i) fp[i]=i;
    sort(node,node+m);   ///贪心思想
    int ans=0;
    for(i=0;i<m;++i){
        x=node[i].x;
        y=node[i].y;
        int xx=findp(x);
        int yy=findp(y);
        if(xx==yy){
            ans=node[i].v;
            break;
        }
        fp[xx]=findp(y+n);  ///x与y的敌人肯定在同一个监狱
        fp[yy]=findp(x+n);  ///同理y与x的敌人肯定在一个监狱
    }
    printf("%d\n",ans);
    return 0;
}