Rev Fact WIP, C++ (gcc)

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#include <iostream>
#define MAXTAM 20
#define MOD 200

using namespace std;

typedef long long ll;

ll rev_fact[MAXTAM];
ll fact[MAXTAM];

ll fast_pow(ll x, ll y, int n)
{
    ll resp = 1, tmp = x;
    while(y > 0)
    {
        if(y & 1)
            resp = (resp * tmp) % n;
        
        tmp = (tmp * tmp) % n;
        y >>= 1;        
    }
    return resp;
}

void factorial()
{
    fact[0] = 1;
    fact[1] = 1;
    
    for(int i = 2; i <= MAXTAM; i++)
    {
        fact[i] = i * fact[i-1];
    }
}

void factorial_inv()
{
    int x= fact[MAXTAM];
    rev_fact[MAXTAM] = fast_pow(x, MOD-2, MOD);
        
    for(int i = MAXTAM-1; i >= 0; i--)
        rev_fact[i] = ((i + 1) * rev_fact[i + 1]) % MOD;
}

int main()
{
    int n, k;
    
    factorial();
    cout << "1)" << fact[20] << endl;
    factorial_inv();
    factorial();
    
    cin >> n;
    cin >> k;
    
    for(int i = MAXTAM-1; i >= 0; i--)
        cout << i << ")" << rev_fact[MAXTAM-3] << endl;
        
    //cout << fact[n]*rev_fact[k]*rev_fact[n-k];
    // cout << fast_pow( 12, 8, 7);
}

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Compilation time: 0.54 sec, absolute running time: 0.08 sec, cpu time: 0.02 sec, memory peak: 3 Mb, absolute service time: 0,63 sec