N! (N factorial) can be quite irritating and difficult to compute for large values of N. So instead of calculating N!, I want to know how many digits are in it. (Remember that N! = N * (N - 1) * (N - 2) * ... * 2 * 1)
Each line of the input will have a single integer N on it 0 < N < 1000000 (1 million). Input is terminated by end of file.
For each value of N, print out how many digits are in N!.
1 3 32000
1 1130271
#include<iostream> #include<cstring> #include<cstdio> #include<algorithm> #include<string.h> #include<cmath> using namespace std; int main() { int n; while(cin>>n) { double a=1; for(double i=1; i<=n; i++) { a+=log(i)/log(10); } int ans=a; cout<<ans<<endl; } return 0; }