bzoj1083: [SCOI2005]繁忙的都市 瓶颈生成树

https://www.lydsy.com/JudgeOnline/problem.php?id=1083

题意:给你一个图,求生成树最大边权最小值

就是求瓶颈生成树(生成树中最大边权最小),最小生成树一定是瓶颈生成树,但是瓶颈生成树不一定是最小生成树,最小瓶颈生成树一定是最小生成树

/**************************************************************
    Problem: 1083
    User: walfy
    Language: C++
    Result: Accepted
    Time:40 ms
    Memory:2420 kb
****************************************************************/
 
//#pragma comment(linker, "/stack:200000000")
//#pragma GCC optimize("Ofast,no-stack-protector")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//#pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define pi acos(-1.0)
#define ll long long
#define vi vector<int>
#define mod 1000000007
#define C 0.5772156649
#define ls l,m,rt<<1
#define rs m+1,r,rt<<1|1
#define pil pair<int,ll>
#define pli pair<ll,int>
#define pii pair<int,int>
#define cd complex<double>
#define ull unsigned long long
#define base 1000000000000000000
#define fio ios::sync_with_stdio(false);cin.tie(0)
 
using namespace std;
 
const double g=10.0,eps=1e-12;
const int N=300+10,maxn=N*N+10,inf=0x3f3f3f3f,INF=0x3f3f3f3f3f3f3f3f;
 
struct edge{
    int u,v,c;
    bool operator <(const edge&rhs)const{
        return c<rhs.c;
    }
}e[maxn];
int fa[N];
int Find(int x)
{
    return fa[x]==x?x:fa[x]=Find(fa[x]);
}
int main()
{
    int n,m;
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)fa[i]=i;
    for(int i=0;i<m;i++)scanf("%d%d%d",&e[i].u,&e[i].v,&e[i].c);
    sort(e,e+m);
    int ans=0;
    for(int i=0;i<m;i++)
    {
        int x=e[i].u,y=e[i].v;
        int fx=Find(x),fy=Find(y);
        if(fx!=fy)
        {
            fa[fx]=fy;
            ans=max(ans,e[i].c);
        }
    }
    printf("%d %d\n",n-1,ans);
    return 0;
}
/***********************
 
***********************/
View Code

 

posted @ 2018-04-27 16:35  walfy  阅读(73)  评论(0编辑  收藏