Codeforces - Minimum Diameter Tree

Topic links: codeforces - Minimum a Diameter Tree

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We put the weight average molecular weight can be near to the edge of the leaves. Why is it correct?

Suppose we put a close to the right edge of the leaf to other points near the leaves, certainly increase.

If you give the non-leaf side, then the other between leaf through this side certainly increase.

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AC Code:

#pragma GCC optimize("-Ofast","-funroll-all-loops")
#include<bits/stdc++.h>
//#define int long long
using namespace std;
const int N=1e5+10;
int n,s,deg[N],cnt;
signed main(){
	cin>>n>>s;
	for(int i=1,a,b;i<n;i++)	scanf("%d %d",&a,&b),deg[a]++,deg[b]++;
	for(int i=1;i<=n;i++)	if(deg[i]==1)	cnt++;
	printf("%.10lf\n",2.0*s/cnt);
	return 0;
}