Watch 10 video solutions for Preimage Size of Factorial Zeroes Function, a hard level problem involving Math, Binary Search. This walkthrough by NeetCodeIO has 13,754 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
Let f(x) be the number of zeroes at the end of x!. Recall that x! = 1 * 2 * 3 * ... * x and by convention, 0! = 1.
f(3) = 0 because 3! = 6 has no zeroes at the end, while f(11) = 2 because 11! = 39916800 has two zeroes at the end.Given an integer k, return the number of non-negative integers x have the property that f(x) = k.
Example 1:
Input: k = 0 Output: 5 Explanation: 0!, 1!, 2!, 3!, and 4! end with k = 0 zeroes.
Example 2:
Input: k = 5 Output: 0 Explanation: There is no x such that x! ends in k = 5 zeroes.
Example 3:
Input: k = 3 Output: 5
Constraints:
0 <= k <= 109