nCr with combinatorics

#include<bits/stdc++.h>

using namespace std;

#define ll      long long
#define MOD     1000000007

ll bigmod(ll base, ll pw, ll mod)
{
    if(pw==0) return 1%mod;

    ll x=bigmod(base,pw/2,mod); //dividing the job into two parts(2^5=2^2&2^2)

    x=(x*x)%mod; //combining the divided parts

    if(pw%2!=0) x=(x*base)%mod; // if(powe if odd left part is being multiplied)

    return x;
}

ll mFact[11111111];
void modFact(ll modval)
{
    mFact[0]=1;
    for(int i=1;i<=10000000;i++){
        mFact[i]=(((mFact[i-1]%modval)*(i%modval))%modval);
    }
}

ll invmod(ll y, ll x, ll modval)
{
    ll down=bigmod(x,modval-2,modval);

    return ((y%modval)*(down%modval))%modval;
}

ll nCr(ll n, ll r, ll modval)
{
    // cout<<n<<" "<<mFact[n]<<endl;
    // cout<<r<<" "<<mFact[r]<<endl;
    // cout<<n-r<<" "<<mFact[n-r]<<endl;
    ll rv=((mFact[n]%modval)*((bigmod(mFact[r],modval-2,modval))%modval)*((bigmod(mFact[n-r],modval-2,modval)%modval)))%modval;

    return rv;
}

ll nCr2(ll n, ll r, ll modval)
{
    ll rv=1;
    ll x=r, y=n-r;
    ll total=1;
    if(x<y) swap(x,y);
    for(ll i=n;i>x;i--){
        total=((total%modval)*(i%modval))%modval;
    }

    return invmod(total,y,modval);
}

int main()
{
    //in1();
    //out1();
    clock_t tStart = clock();

    modFact(MOD);
    cout<<nCr(10,3,MOD)<<endl;
    cout<<nCr2(10,3,MOD)<<endl;

    printf("\n>>Runtime: %.10fs\n", (double) (clock() - tStart) / CLOCKS_PER_SEC);


    return 0;
}