Submission #935492

#	Time	Username	Problem	Language	Result	Execution time	Memory
935492		PM1	Sumtree (INOI20_sumtree)	C++17	10 / 100	86 ms	9692 KiB

Main

#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int mxn=5e5+5,M=1e9+7;
int n,q,r;
ll fuck[mxn],rfuck[mxn];
ll ferma(ll x){
	ll res=1,num=M-2;
	while(num){
		if(num&1)res=(res*x)%M;
		x=(x*x)%M;
		num/=2;
	}
	return res;
}
ll comb(ll x,ll y){
	return (((fuck[y]*rfuck[x])%M)*rfuck[y-x])%M;
}
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>r;
	fuck[0]=1;
	for(int i=1;i<mxn;i++){
		fuck[i]=(fuck[i-1]*i)%M;
		rfuck[i]=ferma(fuck[i]);
	}
	for(int i=1;i<=n-1;i++){
		int x,y;
		cin>>x>>y;
		//v[x].push_back(y);
		//v[y].push_back(x);
	}
	cout<<comb(n-1,n+r-1);
	cin>>q;
	while(q--){

	}
	return 0;
}

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