poj 1861 Networks

 

Special judge 搞了我查了N久。

 

CODE：

 

 

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

const int M = 5001;
const int INF = 0x3f3f3f3f;
int u[4*M], v[4*M], w[4*M];
int p[M], r[4*M];
int n, m, cnt;
int su[4*M], sv[4*M];

int find(int x)
{
    return x == p[x]? x : p[x] = find(p[x]);
}

int cmp(const int i, const int j)
{
    return w[i] < w[j];
}

int Kruskal()
{
    int ans = -INF;
    for(int i = 0; i < n; i++)    p[i] = i;
    for(int i = 0; i < m; i++) r[i] = i;
    sort(r, r+m, cmp);
    for(int i = 0; i < m; i++)
    {
        int e = r[i]; int x = find(u[e]); int y = find(v[e]);
        if(x != y)
        {
            ans = max(ans, w[e]);
            su[cnt] = u[e], sv[cnt++] = v[e];
            p[x] = y;
        }
    }
    return ans;
}

void init()
{
    cnt = 0;
    memset(su, 0, sizeof(su));
    memset(sv, 0, sizeof(sv));
}

int main()
{
    while(~scanf("%d%d", &n, &m))
    {
        init();
        for(int i = 0; i < m; i++)
        {
            scanf("%d%d%d", &u[i], &v[i], &w[i]);
        }
        int ans = Kruskal();
        printf("%d\n", ans);
        printf("%d\n", cnt);
        for(int i = 0; i < cnt; i++)
        {
            printf("%d %d\n", su[i], sv[i]);
        }
    }
    return 0;
}