poj2395

krustra最小生成树

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

#define maxm 10005
#define maxn 2005

struct Edge
{
    int a, b, l;
}edge[maxm];

int father[maxn];
int n, m;

bool operator < (const Edge &a, const Edge &b)
{
    return a.l < b.l;
}

int getanc(int a)
{
    if (a == father[a])
        return a;
    return father[a] = getanc(father[a]);
}

bool connected(int a, int b)
{
    if (getanc(a) == getanc(b))
        return true;
    return false;
}

void merge(int a, int b)
{
    father[getanc(a)] = getanc(b);
}

int main()
{
    //freopen("t.txt", "r", stdin);
    scanf("%d%d", &n, &m);
    for (int i = 0; i < n; i++)
        father[i] = i;
    for (int i = 0; i < m; i++)
    {
        scanf("%d%d%d", &edge[i].a, &edge[i].b, &edge[i].l);
        edge[i].a--;
        edge[i].b--;
    }
    sort(edge, edge + m);
    int tot = 0;
    int ans = 0;
    int i = 0;
    while (tot < n - 1)
    {
        while (i < m && connected(edge[i].a, edge[i].b))
            i++;
        if (i >= m)
            break;
        merge(edge[i].a, edge[i].b);
        if (ans < edge[i].l)
            ans = edge[i].l;
        tot++;
    }
    printf("%d\n", ans);
    return 0;
}