hdu1301 Jungle Roads 基础最小生成树

#include<iostream>
#include<algorithm>
using namespace std;

const int maxn = 10005;
int n, m;
int fa[28];
struct node
{
    int x, y;
    int cost;
}arr[maxn];

void init()
{
    for (int i = 0; i <= maxn; i++)
    {
        fa[i] = i;
    }
}

int find(int x)
{
    if (x != fa[x])
    {
        return find(fa[x]);
    }
    else
        return fa[x];
}

bool cmp(node a, node b)
{
    return a.cost<b.cost;
}

int main()
{
    char c1, c2;
    int k, c;
    while (cin >> n)
    {
        if (n == 0) break;
        int j = 0;    //表示边的数量 
        init();
        for (int i = 1; i<n; i++)
        {
            cin >> c1 >> k;
            while (k--)
            {
                cin >> c2 >> c;
                arr[j].x = c1 - 'A';
                arr[j].y = c2 - 'A';
                arr[j].cost = c;
                j++;
            }
        }
        sort(arr, arr + j, cmp);    //排序 
        int ans = 0;
        for (int i = 0; i<j; i++)
        {
            int fx, fy;
            fx = find(arr[i].x);
            fy = find(arr[i].y);
            if (fx != fy)
            {
                ans += arr[i].cost;
                fa[fy] = fx;
            }
        }
        cout << ans << endl;
    }
    return 0;
}