c++ - FCTRL code chef too slow -

i having issues cpp code in code chef factorial problem. http://www.codechef.com/problems/fctrl keep getting error telling me slow, , wondering if there way speed up?

#include <iostream>  using namespace std;  int divisible_by_5(long &number) {   long hold = 0;   int result = 0;   if(number % 5 == 0)     {       result++;       hold = number/5;       while(hold % 5 == 0)         {           result++;           hold = hold/5;         }     } return result; }  int factorial_expansion(long &number) {   int result = 0;   while(number > 4)     {       result += divisible_by_5(number);       number--;     }   return result; }  int main() {   ios_base::sync_with_stdio(false);    int *p_results_array;    int lines;   cin >> lines;    p_results_array = new int [lines];    for(int = 0; < lines; i++)     {       long input;       cin >> input;        p_results_array[i] = factorial_expansion(input);     }   for(int = 0; < lines; i++)    {       cout << p_results_array[i] << endl;     }   return 0;  } 

edit ended revising everything, , turns out math could've been way better.

#include <iostream> #include <cmath>  using namespace std;  int main() {   int lines;   cin >> lines;    while (lines--)     {       long input;       cin >> input;        int result = 0;        (int = 1; pow(5, i) <= input; i++)         result += input/pow(5, i);        cout << result << endl;    }    return 0; } 

you can several things speed up. hth.

one, separate inputs processing, in main. can time algo, not typing speed. like

   for(int = 0; < lines; i++) {       long input;       cin >> input;       p_results_array[i] = input;     }    for(int = 0; < lines; i++) {       p_results_array[i] = factorial_expansion( (long) p_results_array[i]);     } 

two, keep map of got don't have re-do calcs, such as

#include <map> map<long, long> fivepowers; // , later, check or set known answers 

your divisible_by_5 can enhanced, somethng - , notice changed input type of const long& retain functional interface

int divisible_by_5(const long &number) {   long hold = number;   int result = 0;       while(hold % 5 == 0 )         {           result++;           hold = hold/5;           if ( fivepowers.find(hold) != fivepowers.end() ) return fivepowers[hold] + result;         }   fivepowers[number] = result;   return result; } 

lastly, can improvise factorial_expansion knowing answer 10,11,12,13,14 same 10. first pass, need find out how ahead of 5x are, , bring next number exact 5x. thereafter, reduce 5, not 1. so, math , programming.

int factorial_expansion(const long &number) {   long hold = number;   int result = 0;   int adjuster = number % 5;   if ( adjuster == 0 ) adjuster = 5; // else double-count   while(hold > 4)     {       result += divisible_by_5(hold);       hold -= adjuster;       adjuster = 5;     }   return result; } 

i curious timing get.