POJ 3723 Conscription 最小生成树

想清楚后能发现就要让我们求最小生成树（如果图连通的话，否则就是森林）

//#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<iostream>
#include<sstream>
#include<cmath>
#include<climits>
#include<string>
#include<map>
#include<queue>
#include<vector>
#include<stack>
#include<set>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
#define pb(a) push(a)
#define INF 0x1f1f1f1f
#define lson idx<<1,l,mid
#define rson idx<<1|1,mid+1,r
#define PI  3.1415926535898
template<class T> T min(const T& a,const T& b,const T& c) {
    return min(min(a,b),min(a,c));
}
template<class T> T max(const T& a,const T& b,const T& c) {
    return max(max(a,b),max(a,c));
}
void debug() {
#ifdef ONLINE_JUDGE
#else

    freopen("in.txt","r",stdin);
    //freopen("d:\out1.txt","w",stdout);
#endif
}
int getch() {
    int ch;
    while((ch=getchar())!=EOF) {
        if(ch!=' '&&ch!='
')return ch;
    }
    return EOF;
}

struct Edge
{
    int u,v,w;
    bool operator < (const Edge &ant) const
    {
        return w<ant.w;
    }
};

vector<Edge> edge;
int n,m,k;

int a[20002];
void InitUnionFind()
{
    for(int i=0;i<n+m;i++)
        a[i]=i;
}
int find(int x)
{
    return x==a[x]?x:a[x]=find(a[x]);
}
void marge(int fa,int fb)
{
    a[fa]=fb;
}
int MST()
{
    InitUnionFind();
    sort(edge.begin(),edge.end());
    int res=0;
    int cnt=0;
    for(int i=0;i<edge.size();i++)
    {
        int a=edge[i].u;
        int b=edge[i].v;
        int fa=find(a),fb=find(b);
        if(fa!=fb)
        {
            res+=edge[i].w;
            if(++cnt==n+m-1)break;
            marge(fa,fb);
        }
    }
    return res;
}
int main()
{
    int t;
    scanf("%d",&t);
    for(int ca=1;ca<=t;ca++)
    {
        edge.clear();

        scanf("%d%d%d",&n,&m,&k);
        for(int i=1;i<=k;i++)
        {
            int u,v,w;
            scanf("%d%d%d",&u,&v,&w);
            edge.push_back((Edge){u,v+n,-w});
        }

        printf("%d
",(n+m)*10000+MST());
    }
    return 0;
}