链接：http://poj.org/problem?id=1251

题意：裸奔的最小生成树

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

const int MAX_N = 30;
const int MAX_COST = 9999999;
int cost[MAX_N][MAX_N];
int mincost[MAX_N];
bool used[MAX_N];
void init() {
    for (int i = 0; i < MAX_N; i++) {
        used[i] = false;
        mincost[i] = MAX_COST;
        for (int j = 0; j < MAX_N; j++) {
            cost[i][j] = MAX_COST;
        }
    }
}
int Prim(int n) {
    mincost[1] = 0;
    int res = 0;
    for (int i = 1; i <= n; i++) {
        int index = -1;
        int mmin = MAX_COST;
        for (int j = 1; j <= n; j++) {
            if (!used[j] && mincost[j] < mmin) {
                index = j;
                mmin = mincost[j];
            }
        }
        res += mincost[index];
        used[index] = true;
        for (int j = 1; j <= n; j++) {
            mincost[j] = min(mincost[j], cost[index][j]);
        }
    }
    return res;
}
int main()
{
    int n;
    char ch;
    int cnt;
    char target;
    int costt;
    while (cin >> n) {
        if (!n)  break;
        init();
        for (int i = 1; i < n; i++) {
            cin >> ch;
            cin >> cnt;
            int st = ch - 'A' + 1;
            for (int j = 1; j <= cnt; j++) {
                cin >> target;
                cin >> costt;
                int dest = target - 'A' + 1;
                cost[st][dest] = cost[dest][st] = costt;
                //cout << st << "->" << dest << "  " << costt;
            }
        }
        int res = Prim(n);
        cout << res << endl;
    }

    return 0;
}