POJ 1861 & ZOJ 1542 Network（最小生成树之Krusal）

题目链接：

PKU:http://poj.org/problem?id=1861

ZJU:http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=542

Description

Input

Output

Sample Input

4 6
1 2 1
1 3 1
1 4 2
2 3 1
3 4 1
2 4 1

Sample Output

1
4
1 2
1 3
2 3
3 4

Source

PS:

貌似题目的案例有点问题，卡了好久！

代码如下：

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int inf = 9999999;
const int maxn = 15017;
int father[maxn];
struct edge
{
    int x,y,v;
};
struct edge ed[maxn],ansa[maxn];

bool cmp(edge a,edge b)
{
    return a.v<b.v;
}

int find(int x)
{
    if(x==father[x])
        return x;
    return father[x]=find(father[x]);
}

void Krusal(int n,int m)
{
    int i,fx,fy,cnt;
    int ans=0;
    for(i = 1; i <= n; i++)
        father[i]=i;
    sort(ed,ed+m,cmp);//对边的排序
    cnt=0;
    int max=-1;
    for(i=0; i<m; i++)
    {
        fx=find(ed[i].x);
        fy=find(ed[i].y);
        if(fx!=fy)
        {
            ans+=ed[i].v;
            father[fx]=fy;
            ansa[cnt].x=ed[i].x;
            ansa[cnt++].y=ed[i].y;
            if(max<ed[i].v)
                max=ed[i].v;
        }
    }
    printf("%d\n%d\n",max,cnt);
    for(i=0; i<cnt; i++)
        printf("%d %d\n",ansa[i].x,ansa[i].y);
}

int main()
{
    int t;
    int n, m;
    int a, b, k;

    while(scanf("%d %d",&n,&m)!=EOF)
    {
        for(int i = 0; i < m; i++)
        {
            scanf("%d %d %d",&a,&b,&k);
            ed[i].x=a,ed[i].y=b,ed[i].v=k;
        }
        Krusal(n,m);
    }
    return 0;
}