Cod sursa(job #2151725)

Utilizator Daria09Florea Daria Daria09 Data 4 martie 2018 20:33:46
Problema Dirichlet Scor 4
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.69 kb
#include <iostream>
#include <fstream>
#define MOD  9999991
using namespace std;
ifstream f("dirichlet.in");
ofstream g("dirichlet.out");
int fact[1000005];
int invers(long long x,long long y)
{
    long long sol=1;
    while(y)
    {
        if(y&1)sol=(1LL*sol*x)%MOD;
        x=(1LL*x*x)%MOD;
        y>>=1;
    }
    return sol;
}
void factorial()
{
    int i; fact[1]=1;
    for(i=2;i<=1000000;i++)fact[i]=(1LL*fact[i-1]*i)%MOD;
}
int comb(int n,int k)
{
    if(!n||!k)return 1;
    return (1LL*fact[n]*invers(1LL*fact[k]*fact[n-k]%MOD,MOD-2))%MOD;
}
int main()
{
    int n;
    f>>n;
    factorial();
    g<<(comb(2*n,n)*invers(n+1,MOD-2))%MOD;
    return 0;
}