Jungle Roads

传送门

• 最小生成树模板题

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

const int N = 27, INF = 0x3f3f3f3f;
int dist[N], vis[N], g[N][N];

int n;
int prim(){
	memset(dist, INF, sizeof dist);
	memset(vis, 0, sizeof vis);
	int res = 0;
	for(int i = 0; i < n; i ++){
		int t = -1;
		for(int j = 1; j <= n; j ++)
			if(!vis[j] && (t == -1 || dist[t] > dist[j]))
				t = j;
		if(i) res += dist[t];
		for(int j = 1; j <= n; j ++)
			dist[j] = min(dist[j], g[t][j]);
		vis[t] = true;
		//cout << "i = " << i << " res = " << res << endl;
	}
	return res;
}
int main(){
	while(cin >> n){
		if(!n)
			break;
		char op;
		memset(g, INF, sizeof g);
		for(int j = 1; j < n; j ++){
			int k;
			cin >> op >> k;
			for(int i = 1; i <= k; i ++){
				int w;
				char c;
				cin >> c >> w;
				g[op - 'A' + 1][c - 'A' + 1] = g[c - 'A' + 1][op - 'A' + 1] = min(g[op - 'A' + 1][c - 'A' + 1], w);
			}
		}
		cout << prim() << endl;
	}
	
	return 0;
}