hdu 3367 Pseudoforest 最大生成树★

#include <cstdio>
#include <cstring>
#include <vector>
#include <algorithm>
using namespace std;

const int maxn = 100005;
int n, m;
struct node
{
    int u, v, c;
}g[maxn];
long long ans;
int fa[maxn];
int ff[maxn];
int ee[maxn];

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

void init(){
    memset(ff, false, sizeof(ff));
    memset(ee, false, sizeof(ee));
    for (int i = 0; i < n; i++){
        fa[i] = i;
    }
}

int find(int x){
    if (x == fa[x])
        return x;
    else
        return fa[x] = find(fa[x]);
}

void Union(int x, int y, int z){
    int a = find(x);
    int b = find(y);
    if (a == b){
        if (ff[a])
            return;
        ans += z;
        ff[a] = true;
    }
    else{
        if (ff[a] && ff[b])
            return;
        ans += z;
        fa[b] = a;
        if (ff[a] || ff[b])
            ff[a] = true;
    }
}

int main(){
    while (~scanf("%d%d", &n, &m)){
        if (n == 0 && m == 0)
            break;
        init();
        int u, v, c;
        for (int i = 0; i < m; i++){
            scanf("%d%d%d", &u, &v, &c);
            g[i].u = u;
            g[i].v = v;
            g[i].c = c;
        }
        //克鲁斯卡尔
        sort(g, g + m, cmp);    //按边从小到大排列
        ans = 0;
        for (int i = 0; i < m; i++){
            Union(g[i].u, g[i].v, g[i].c);
        }
        printf("%lld
", ans);
    }
    //system("pause");
    return 0;
}