zoukankan      html  css  js  c++  java
  • 最大边和最小边之差最小的生成树 UVA 1394

    题目大意:给你n个点的图,求苗条度(最大边减最小编)尽量小的生成树

    思路:sort以后暴力枚举区间即可

    //看看会不会爆int!数组会不会少了一维!
    //取物问题一定要小心先手胜利的条件
    #include <bits/stdc++.h>
    using namespace std;
    #define LL long long
    #define ALL(a) a.begin(), a.end()
    #define pb push_back
    #define mk make_pair
    #define fi first
    #define se second
    const int inf = 0x3f3f3f3f;
    const int maxn = 100 + 5;
    struct Edge{
        int u, v, val;
        Edge(int u = 0, int v = 0, int val = 0): u(u), v(v), val(val){}
        bool operator < (const Edge &a) const{
            return val < a.val;
        }
    }edges[maxn * maxn];
    int par[maxn];
    int n, m;
    
    void init(){for (int i = 1; i <= n; i++) par[i] = i;}
    int pfind(int x){
        if (par[x] == x) return x;
        return par[x] = pfind(par[x]);
    }
    
    bool solve(int l, int r){
        for (int i = l; i <= r; i++){
            int pu = pfind(edges[i].u);
            int pv = pfind(edges[i].v);
            if (pu == pv) continue;
            par[pu] = pv;
        }
        int p = pfind(1);
        for (int i = 2; i <= n; i++){
            if (p != pfind(i)) return false;
        }
        return true;
    }
    
    int main(){
        while (scanf("%d%d", &n, &m) && n){
            for (int i = 1; i <= m; i++) {
                int u, v, val; scanf("%d%d%d", &u, &v, &val);
                edges[i] = Edge(u, v, val);
            }
            int ans = inf;
            sort(edges + 1, edges + m + 1);
            for (int l = 1; l <= m; l++){
                init();
                for (int r = l; r <= m; r++){
                    if (solve(l, r)){
                        ans = min(ans, edges[r].val - edges[l].val);
                        break;
                    }
                }
            }
            if (ans == inf) ans = -1;
            printf("%d
    ", ans);
        }
        return 0;
    }
    View Code
  • 相关阅读:
    Java8新特性
    中文乱码常见解决方案
    Btrace的使用方法
    jquery获取的html元素和document获取的元素的区别
    Easy UI分页控件修改刷新方法后触发两次请求
    js获取字符串的实际长度并截断实际长度
    js生成唯一的uuid
    easy UI动态赋值
    springmvc+shiro认证框架配置
    shiro配置unauthorizedUrl,无权限抛出无权限异常,但是不跳转
  • 原文地址:https://www.cnblogs.com/heimao5027/p/5877267.html
Copyright © 2011-2022 走看看