Getting WA in LENGFACT!

[tejk]

#include <iostream>
#include <cmath>
using namespace std;
int main(){
    long long int cases,n,i;
    double sum;
    cin >> cases;
    for(i=1;i<=cases;++i){
        cin >> n; 
        if((n==1)||(n==0))
            cout << "1" << endl;    
        else {
            cout <<  int((log(2*M_PI*n)/2+n*(log(n)-log(M_E)))/log(10))+1 << endl;
        }
    }
    return 0;
}

Any problem with the formula??

[leppyr64]

Yes. Have you tried a maximal sized test case?

[tejk]

Ok I tried and my formula doesn't work with the maximal sized test case!! Do you have another formula?

[leppyr64]

Why doesnt your formula work? Why did you think it would work?

[spalac24]

Remember that in c++ int has a limited size.

[lonelynerd]

I am getting TLE
Please help me:

Removed after AC

[leppyr64]

Cin and cout are slow. Use scanf and printf.

[lonelynerd]

Still getting TLE

Removed

[kokosek]

y<=5*10^9
O(n) is too slow.

And in printing int is not enough.

[lonelynerd]

y<=5*10^9
O(n) is too slow.

And in printing int is not enough.

Now i have converted it into O(log n) but still getting TLE:

Removed

Can any mathematical formulae be derived so that it becomes O(1) or is my approach wrong?

[spalac24]

Yes, there exist a formula.