Solution of Light OJ 1067-Combinations

See the problem Light OJ 1067

#include<bits/stdc++.h> #define ll long long using namespace std; ll n, r, t, i, ans, cs=1, up, dwn, fac[1000009]; const ll mod=1000003; ll bigmod(ll b, ll p){ if(p==0) return 1; ll x=bigmod(b, p/2); x=(x*x)%mod; if(p%2==1)x=(x*b)%mod; return x; } int main(){ fac[0]=1; for(i=1; i<=1000000; i++){ fac[i]=(fac[i-1]*i)%mod; } cin>>t; while(t--){ cin>>n>>r; up=fac[n]; dwn=(fac[n-r]*fac[r])%mod; ans=up*bigmod(dwn, mod-2); cout<<"Case "<<cs++<<": "<<ans%mod<<endl; } return 0; }