Factorial Trailing Zeroes Problem & Solution

Given an integer n, return the number of trailing zeroes in n!.

See the factorial trailing zeroes problem on LeetCode.

C++ Solution

#pragma GCC optimize("Ofast")
#pragma GCC optimization("unroll-loops")

static const int _=[](){std::ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();

class Solution {
public:
  int trailingZeroes(int n) {
    int result = 0;
    
    // Sums up the powers of 5 at each step, skipping other factors than 5.
    while (n > 0) {
      result += n / 5;
      n /= 5;
    }
    
    return result;
  }
};

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