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  1. 		/*
  2. 			//! In The Name Of Allah
  3.  
  4.  
  5.  
  6.  
  7. 		*/                                                                                                                                                  
  8.   #include<bits/stdc++.h>
  9.   using namespace std;
  10.   #define tt int t;cin>>t;while(t--)
  11.   #define itr(i,a) for(int i=0;i<a;i++)
  12. #define ittr(i,bg,a) for(int i=bg;i<a;i++)
  13.   #define yes cout<<"YES"<<endl
  14.   #define no cout<<"NO"<<endl
  15.   #define ll long long
  16.   #define endd cout<<endl
  17.   #define vc(v, n) vector<ll> v(n)  
  18.   #define srt(v) sort(v.begin(), v.end())
  19. #define rsrt(v) sort(v.rbegin(), v.rend())
  20. #define pb(a,x) a.push_back(x)
  21. #define MOD 1000000007
  22.   #define f first
  23.   #define sc second
  24. #define endl '\n'
  25. const int N=1e5+5;
  26. vector<ll>fact_ar(N,1),modinv(N,1);
  27. ll power(ll x,ll mod){
  28.     if(mod<0) return 0;
  29.     ll ans=1;
  30.     while(mod){
  31.         if(mod%2==0){
  32.             x=(x*x)%MOD;
  33.             mod/=2;
  34.         }
  35.         else{
  36.             ans=(ans*x)%MOD;
  37.             mod--;
  38.         }
  39.     }
  40.     return ans;
  41. }
  42. void precomp(){
  43.     fact_ar[0]=1;
  44.     for(int i=1;i<N;i++){
  45.         fact_ar[i]=(fact_ar[i-1]*i)%MOD;
  46.         modinv[i]=power(fact_ar[i],MOD-2);
  47.  
  48.     }
  49. }
  50.  
  51. ll ncr(ll n,ll r){
  52.     if(n<0||r<0||r>n) return 0;
  53.     ll numo=fact_ar[n];
  54.     ll ans=((fact_ar[n]*modinv[r])%MOD*modinv[n-r])%MOD;
  55.     return ans;
  56. }
  57.  
  58.  
  59.   int main(){
  60.     ios::sync_with_stdio(false);
  61.       cin.tie(nullptr);
  62.     // sieve();
  63.    // divis();
  64.    precomp();
  65.   tt{
  66.     ll n,r;
  67.     cin>>n>>r;
  68.     cout<<ncr(n,r)<<endl;
  69.  
  70.  
  71.   }
  72.   }
  73.  
  74.  
  75.  
Success #stdin #stdout 0.03s 5284KB
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https://ideone.com/3zUSPr
fact
language:
C++ (gcc 8.3)
created:
3 days ago
visibility:
public

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