n!末尾有多个个零

#include <stdint.h>
#include <iostream>
using namespace std;
unsigned fun(unsigned n) {
  unsigned sum5 = 0;
  int t = 0;
  for (int i = 5;i <= n;i += 5) {
    t = i;
    while (t >= 5) {
      if (0 == t % 5) {
        ++sum5;
      }
      t /= 5;
    }
  }
  return sum5;
}
int fun1(int n) {
  unsigned cnt = 0;
  while (n /5 != 0) {
    cnt = cnt + n/5;
    n /= 5;
  }
  return cnt;
}
int main() {
  unsigned n;
  n = 26;
  for (int i = 0;i < 1000000;i++) {
    //fun(n);     // 0.054s
    fun1(n);      // 0.024s
  }

  return 0;
}