题目1028：继续畅通工程(最小生成树应用)

题目链接：http://ac.jobdu.com/problem.php?pid=1028

详解链接：https://github.com/zpfbuaa/JobduInCPlusPlus

参考代码：

#include <stdio.h>
#include <iostream>
#include <algorithm>
#include <string.h>
#include <cmath>
#define MAX_SIZE 110
 
using namespace std;
 
int tree[MAX_SIZE];
 
int findRoot(int x){
    if(tree[x] == -1) return x;
    else{
        int tmp = findRoot(tree[x]);
        tree[x] = tmp;
        return tmp;
    }
}
 
struct Edge{
    int a;
    int b;
    int cost;
    int exist;
    bool operator < (const Edge &A)const{
        return cost < A.cost;
    }
};
 
int n;
 
int main(){
    while(scanf("%d",&n)!=EOF && n!=0){
        Edge edge[n*(n-1)/2+1];
        for(int i = 1 ; i <= n ; i++){
            tree[i] = -1;
        }
        for(int i = 1 ; i <= n*(n-1)/2 ; i++){
            scanf("%d%d%d%d",&edge[i].a,&edge[i].b,&edge[i].cost,&edge[i].exist);
            if(edge[i].exist==1){
                int a = findRoot(edge[i].a);
                int b = findRoot(edge[i].b);
                if(a!=b){
                    tree[a] = b;
                }
            }
        }
        sort(edge+1,edge+1+n*(n-1)/2);
        int ans = 0;
        for(int i = 1 ; i <= n*(n-1)/2 ; i++){
             
            int a = findRoot(edge[i].a);
            int b = findRoot(edge[i].b);
            if(a!=b){
                tree[a] = b;
                ans+=edge[i].cost;
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}
/**************************************************************
    Problem: 1028
    User: zpfbuaa
    Language: C++
    Result: Accepted
    Time:20 ms
    Memory:1520 kb
****************************************************************/