LightOJ 1045 Digits of Factorial Solution

Problem Link:  https://lightoj.com/problem/digits-of-factorial

 Solution in C++: 

///La ilaha illellahu muhammadur rasulullah

///******Bismillahir-Rahmanir-Rahim******///

///Abul Hasnat  Tonmoy

///Department of CSE,23rd batch

///Islamic University,Bangladesh

///**********ALLAH IS ALMIGHTY************///

#include<bits/stdc++.h>

using namespace std;

typedef long long ll;

const int mx=1e6+9;

double lg[mx];

void preCal()

{

    lg[0]=0;

    for(int i=1; i<=mx; i++)

    {

        lg[i]=lg[i-1]+log10(i);

    }

}

int main()

{

    ll t,ts=1,base,n,ans;

    preCal();

    cin>>t;

    while(t--)

    {

        cin>>n>>base;

        ans=lg[n]/log10(base);

        printf("Case %d: %d\n",ts++,ans+1);

    }

}