uva 11857

MST求最大的那個邊

SubmissionErr 別解這題(不知道此code有無錯誤 因為平台廢掉了)

//====================================================================||
//                                                                    ||
//                                                                    ||
//                         Author : GCA                               ||
//                  6AE7EE02212D47DAD26C32C0FE829006                  ||
//====================================================================||
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <climits>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <cctype>
#include <utility>
using namespace std;
#ifdef ONLINE_JUDGE
#define ll "%lld"
#else
#define ll "%I64d"
#endif
typedef unsigned int uint;
typedef long long int Int;
#define Set(a,s) memset(a,s,sizeof(a))
#define Write(w) freopen(w,"w",stdout)
#define Read(r) freopen(r,"r",stdin)
#define Pln() printf("\n")
#define I_de(x,n)for(int i=0;i<n;i++)printf("%d ",x[i]);Pln()
#define De(x)printf(#x"%d\n",x)
#define For(i,x)for(int i=0;i<x;i++)
#define CON(x,y) x##y
#define Pmz(dp,nx,ny)for(int hty=0;hty<ny;hty++){for(int htx=0;htx<nx;htx++){\
    printf("%d ",dp[htx][hty]);}Pln();}
#define M 1000005
#define PII pair<int,int>
#define PB push_back
#define oo INT_MAX
#define Set_oo 0x3f
#define Is_debug true
#define debug(...) if(Is_debug)printf("DEBUG: "),printf(__VA_ARGS__)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();it++)
#define eps 1e-6
bool xdy(double x,double y){return x>y+eps;}
bool xddy(double x,double y){return x>y-eps;}
bool xcy(double x,double y){return x<y-eps;}
bool xcdy(double x,double y){return x<y+eps;}
int min3(int x,int y,int z){
    int tmp=min(x,y);
    return min(tmp,z);
}
int max3(int x,int y,int z){
    int tmp=max(x,y);
    return max(tmp,z);
}
struct edge{
    int x,y,w;
}edges[M];
int n,m;
int p[M];
int rank[M];
bool cmp(edge a,edge b){
    return a.w<b.w;
}
void init(){
    for(int i=0;i<n;i++){
        rank[i]=0;
        p[i]=i;
    }
}
int getf(int x){
    if(x!=p[x])p[x]=getf(p[x]);
    return p[x];
}
void _union(int x,int y){

    if(rank[x]>rank[y])p[y]=x;
    else{
        p[x]=y;
        if(rank[x]==rank[y])rank[y]++;
    }

}
void solve(){
    sort(edges,edges+m,cmp);
    int mx=0;
    int cm=0;
    for(int i=0;i<m;i++){
        int x=edges[i].x;
        int y=edges[i].y;
        int w=edges[i].w;
        int fx=getf(x);
        int fy=getf(y);
        if(fx!=fy){
            _union(fx,fy);
            cm++;
            mx=max(mx,w);
        }
    }
    if(cm+1<n)printf("IMPOSSIBLE\n");
    else printf("%d\n",mx);
}
int main() {
    ios_base::sync_with_stdio(0);
    while(~scanf("%d%d",&n,&m)&&n+m){
        init();
        for(int i=0;i<m;i++){
            scanf("%d%d%d",&edges[i].x,&edges[i].y,&edges[i].w);
        }
        solve();
    }

















}