AtCoder 328. E Modulo MST_e - modulo mst

暴力枚举所有选边的可能, 最后再判断是否是连通图

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
 
class Main {
    static class Edge {
        int a, b;
        long w;
 
        public Edge(int a, int b, long w) {
            this.a = a;
            this.b = b;
            this.w = w;
        }
    }
    static int n, m;
    static long k, ans = Long.MAX_VALUE;
    static Edge[] e;
    static List<Edge> lis = new ArrayList<>();
 
    static int[] p;
    public static int find(int x) {
        if (x != p[x]) p[x] = find(p[x]);
        return p[x];
    }
 
    public static void add(int x, int y) {
        int px = find(x), py = find(y);
        if (px == py) return ;
        p[px] = py;
    }
 
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
 
        n = sc.nextInt(); m = sc.nextInt(); k = sc.nextLong();
        e = new Edge[m + 10];
        p = new int[n + 10];
        for (int i = 1; i <= m; i ++ ) {
            int x = sc.nextInt(); int y = sc.nextInt(); long c = sc.nextLong();
            e[i] = new Edge(x, y, c);
        }
        dfs(1, 0);
        System.out.println(ans);
    }
 
    public static void dfs(int now, int x) {
        if (x == n - 1) {
            long sum = 0;
            for (int i = 1; i <= n; i ++ ) p[i] = i; // 并查集的初始化
            // 用并查集判断是否是连通图
            for (int i = 0; i < lis.size(); i ++ ) {
                Edge t = lis.get(i);
                sum += t.w;
                add(t.a, t.b);
            }
 
            for (int i = 2; i <= n; i ++ ) {
                if (find(i) != find(i - 1)) return ;
            }
 
            ans = Math.min(ans, sum % k); // 尝试更新答案
            return ;
        }
        if (now >= m + 1) return ;
 
        dfs(now + 1, x);
        lis.add(e[now]);
        dfs(now + 1, x + 1);
        lis.remove(e[now]);
    }
}