ZOJ 1406 Jungle Roads 【kruskal】

1406

//2621190 	2011-08-10 10:31:25 	Accepted 	1406 	C++ 	0 	184 	ylwh!
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <algorithm>
#define N 27
using namespace std;
struct edge
{
	int x, y;
	int cost;
}e[N*N/2];
int root[N];
bool cmp(struct edge a, struct edge b)
{
	return a.cost < b.cost;
}
int find_root(int x)
{
	int temp;
	temp = x;
	while(temp != root[temp])
		temp = root[temp];
	root[x] = temp;
	return temp;
}
int main()
{
	int n, k, temp, flag, d[N], cnt;
	int i, j, ans;
	char ch;
	while(scanf("%d", &n), n)
	{
		cnt = -1;
		ans = 0;
		for(i=0; i<n; i++)
			root[i] = i;
		for(i=0; i<n-1; i++)
		{
			scanf(" %c%d", &ch, &k);
			temp = ch - 'A';
			while(k--)
			{
				scanf(" %c%d", &ch, &flag);
				e[++cnt].x = temp;
				e[cnt].y = ch - 'A';
				e[cnt].cost = flag;
			}
		}
		sort(e, e+cnt+1, cmp);
		int a, b;
		for(i=0; i<=cnt; i++)
		{
			a = find_root(e[i].x);
			b = find_root(e[i].y);
			if(a != b)
			{
				root[b] = a;
				ans += e[i].cost;
			}
		}
		printf("%d\n", ans);
	}
    return 0;
}