题解 | #继续畅通工程#注意如果已经建好的话要把花费设为0

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;
public class Main {
    private static int[] parents;
    private static class Edge {
        private final int from, to, weight;
        private Edge(int from, int to, int weight) {
            this.from = from;
            this.to = to;
            this.weight = weight;
        }
    }
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNextInt()) {
            int n = sc.nextInt();
            if (n == 0) break;
            List<Edge> edges = new ArrayList<>();
            for (int i = 0; i < n * (n - 1) / 2; i++) {
                int from = sc.nextInt();
                int to = sc.nextInt();
                int weight = sc.nextInt();
                int flag = sc.nextInt();
                if (flag == 1) weight = 0;
                edges.add(new Edge(from, to, weight));
            }
            edges.sort(Comparator.comparingInt(o -> o.weight));
            parents = new int[n + 1];
            for (int i = 1; i <= n; i++) parents[i] = i;
            int ans = 0;
            for (Edge edge : edges) {
                int a = find(edge.from);
                int b = find(edge.to);
                if (a != b) {
                    parents[a] = b;
                    ans += edge.weight;
                }
            }
            System.out.println(ans);
        }
    }
    private static int find(int x) {
        return x == parents[x] ? x : (parents[x] = find(parents[x]));
    }
}