Codeforces Round＃525（Div.2）Ehab and a component choosing problem CodeForces

题意：

有一个拥有 n 个节点的树，你要选 k 个联通块出来，使得这 k 个联通块中所有点的权值总和 sum 与联通块个数 k 的比值最大，多解时应使联通块的数量尽可能地多

#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<string.h>
#include<queue>
#include<stack>
#include<list>
#include<map>
#include<set>
#include<vector>
using namespace std;
typedef long long int ll;
const int maxn =3e5+7;
const int maxm=10000;
const int mod =1e9+7;
const int INF=0x3f3f3f3f;
const double eps=1e-8;int n,a[maxn],cnt;
vector<int>edge[maxn];
ll maxx=-mod;
ll dfs(int u,int pre,bool flag)
{ll sum=a[u];for(int v:edge[u])if(v!=pre)sum+=max(0ll,dfs(v,u,flag));if(!flag)maxx=max(maxx,sum);else if(sum==maxx)cnt++,sum=0;return sum;
}int main()
{scanf("%d",&n);for(int i=1;i<=n;i++)scanf("%d",&a[i]);for(int i=1;i<n;i++){int u,v; scanf("%d%d",&u,&v);edge[u].push_back(v);edge[v].push_back(u);}dfs(1,1,false),dfs(1,1,true);printf("%lld %d\n",cnt*maxx,cnt);return 0;
}

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Codeforces Round＃525（Div.2）Ehab and a component choosing problem CodeForces - 1088E

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