CCF-CSP题解 201812-4 数据中心

题目要求最长边最小的生成树。好吧，这就是一道kruskal MST题。

#include <bits/stdc++.h>
const int maxn = 50000;
const int maxm = 100000;

using namespace std;

struct tEdge
{
    int u, v;
    int t;
    bool operator < (const tEdge &y) const
    {
        return t < y.t;
    }
};
tEdge edge[maxm+10];
int cnt = 1;

int fa[maxn+10];

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

int main()
{
    int n, m, root;
    scanf("%d%d%d", &n, &m, &root);

    for (int i = 1, u, v, t; i <= m; i++)
    {
        scanf("%d%d%d", &u, &v, &t);
        edge[cnt].u = u;
        edge[cnt].v = v;
        edge[cnt++].t = t;
    }

    sort(edge + 1, edge + 1 + m);

    for (int i = 1; i <= n; i++)
        fa[i] = i;

    int ans = -1;
    for (int i = 1, temp = 0; temp != n - 1; i++)
    {
        int rx = getFa(edge[i].u), ry = getFa(edge[i].v);
        if (rx != ry)
        {
            fa[rx] = ry;
            temp ++;
            ans = edge[i].t;
        }
    }

    printf("%d\n", ans);

    return 0;
}