修复公路

#include <bits/stdc++.h>
using namespace std;
int n, m;
struct Line
{
    int x, y, t;
} a[100000 + 5];
bool cmp(Line a, Line b)
{
    return a.t < b.t;
}
int fa[1000 + 5];
int cnt[1000 + 5];
int findFa(int x)
{
    if (x == fa[x])
        return x;
    return fa[x] = findFa(fa[x]);
}
int main()
{
    cin >> n >> m;
    for (int i = 1; i <= m; i++)
        cin >> a[i].x >> a[i].y >> a[i].t;
    sort(a + 1, a + m + 1, cmp);
    for (int i = 1; i <= n; i++)
    {
        fa[i] = i;
        cnt[i] = 1;
    }
    for (int i = 1; i <= m; i++)
    {
        int faX = findFa(a[i].x);
        int faY = findFa(a[i].y);
        if (faX != faY)
        {
            if (cnt[faX] < cnt[faY])
                swap(faX, faY);
            fa[faY] = faX;
            cnt[faX] += cnt[faY];
        }
        if (cnt[faX] == n)
        {
            cout << a[i].t;
            return 0;
        }
    }
    cout << "-1\n";
    return 0;
}