POJ 1287 Networking【kruskal模板题】

传送门：http://poj.org/problem?id=1287

题意：给出n个点 m条边 ，求最小生成树的权

思路：最小生树的模板题，直接跑一遍kruskal即可

代码：

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<string.h>
using namespace std;
const int maxn = 5005;
struct node
{
    int u;
    int v;
    int w;
    bool operator< (const node &a)
    {
        return w < a.w;
    }
} edges[maxn];
int f[maxn];
int find(int x)
{
    return f[x] = f[x] == x ? x : find(f[x]);
}
int kruskal(int n, int m)
{
    for(int i = 1; i <= n; i++)
        f[i] = i;
    int cnt = 0;
    int ans = 0;
    for(int i = 1; i <= m; i++)
    {
        int u = edges[i].u;
        int v = edges[i].v;
        int w = edges[i].w;
        int t1 = find(u);
        int t2 = find(v);
        if(t1 != t2)
        {
            ans += w;
            f[t1] = t2;
            cnt++;
        }
        if(cnt == n - 1)
            break;
    }
    if(cnt < n - 1)
        return -1;
    else
        return ans;
}
int main()
{
    int n;
    while(scanf("%d", &n), n)
    {
        int m;
        scanf("%d", &m);
        for(int i = 1; i <= m; i++)
        {
            scanf("%d%d%d", &edges[i].u, &edges[i].v, &edges[i].w);
        }
        sort(edges + 1, edges + m + 1);
        int ans = kruskal(n, m);
        cout << ans << endl;
    }
}