Input: N = 4, a[] = {7, 15, 6, 3}, h = 8
Output: 5
Explanation:  If Koko eats 5 bananas/hr, he will take 2, 3, 2, and 1 hour to eat the piles accordingly. So, he will take 8 hours to complete all the piles.  

Input: N = 5, a[] = {25, 12, 8, 14, 19}, h = 5
Output: 25
Explanation: If Koko eats 25 bananas/hr, he will take 1, 1, 1, 1, and 1 hour to eat the piles accordingly.

Disclaimer: Here is the practice link to help you assess your knowledge better. It's highly recommend trying to solve it before looking at the solution.

Brute-Force Approach

Algorithm

The problem is about finding the minimum eating speed such that Koko can finish all bananas within h hours. The extremely naive approach is to check all possible answers from 1 to max(a[]). The minimum number for which the required time is less than or equal to h is our answer.

Find the largest pile size (max of the array).
Loop through all possible speeds from 1 to this maximum value.
For each speed, calculate the total hours needed. For each pile, compute the time as ceil(pile / speed).
Sum up the hours for all piles.
If the total hours is less than or equal to the allowed hours, return this speed as the answer.

Code