以hdu1879为例，附上一份板子：hdu1879

//hdu1879
#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<algorithm>
using namespace std;
typedef long long ll;
const int maxn = 1e8;
int n;
int m;
struct Node {
	int start;
	int end;
	int w;
}edge[maxn];
int pre[maxn];
int sum;
bool cmp(Node a, Node b)
{
	return a.w < b.w;
}
int find(int x) {
	if (x == pre[x])
		return x;
	return pre[x] = find(pre[x]);
}
void Kruscal(int x, int y, int n) {
	int fx = find(x);
	int fy = find(y);
	if (fx != fy) {
		pre[fx] = fy;
		sum += edge[n].w;
	}
}
int main()
{
	while (cin >> n) {
		if (n == 0)break;
		int m = n*(n - 1) / 2;

		for (int i = 0; i <= 110; i++)
			pre[i] = i;

		int u, v, w, flag;
		for (int i = 1; i <= m; i++) {
			cin >> u >> v >> w >> flag;
			edge[i].start = u;
			edge[i].end = v;
			if (flag == 1)
				edge[i].w = 0;
			else
				edge[i].w = w;
		}

		sort(edge + 1, edge + 1 + m, cmp);

		sum = 0;
		for (int i = 1; i <= m; i++) {//遍历所有的边，生成树
			Kruscal(edge[i].start, edge[i].end, i);
		}
		cout << sum << endl;
	}
	return 0;
}