Submission #632477

#	Time	Username	Problem	Language	Result	Execution time	Memory
632477		codr0	Sumtree (INOI20_sumtree)	C++14	10 / 100	51 ms	10984 KiB

Main

#include <bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>

#define F first
#define S second
#define FOR(i,a,b) for(int i=a;i<=b;i++)
#define FORR(i,a,b) for(int i=a;i>=b;i--)
#define err(x) cerr<<#x<<"="<<x<<'\n'
#define lc 2*id
#define rc 2*id+1
#define dmid int mid=(r+l)/2
#define all(x) x.begin(),x.end()
#define SZ(x) (int)x.size()
#define pb push_back
#define maxm(a,b) a=max(a,b)
#define minm(a,b) a=min(a,b)
#define bit(i,j) ((j>>i)&1)

using namespace std;
const int md=1e9+7;
const int N=5e5+4;
int fct[N],inv[N];

	int pw(int a,int b){
		int rt=1;
		while(b){
			if(b&1) rt=1LL*rt*a%md;
			a=1LL*a*a%md;
			b/=2;
		}
		return rt;
	}

	int C(int r,int n){
		return (1LL*(1LL*fct[n]*inv[r]%md)*inv[n-r]%md);
	}

	int32_t main(){
	iostream::sync_with_stdio(0); cin.tie(0);
	
	fct[0]=1; FOR(i,1,N-1) fct[i]=1LL*fct[i-1]*i%md;
	inv[N-1]=pw(fct[N-1],md-2); FORR(i,N-2,0) inv[i]=1LL*inv[i+1]*(i+1)%md;
	int n,r; cin>>n>>r;
	FOR(i,1,n-1){
		int u,v; cin>>u>>v;
	}
	int q; cin>>q;
	assert(q==0);
	cout<<C(n-1,n-1+r)<<'\n';

	return 0;
	}

• Subtask 1: 10 / 10
• Subtask 2: 0 / 20
• Subtask 3: 0 / 20
• Subtask 4: 0 / 20
• Subtask 5: 0 / 30