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907. Koko Eating Bananas

Array Binary Search

Problem - Koko Eating Bananas

Medium

Koko loves to eat bananas. There are n piles of bananas, the ith pile has piles[i] bananas. The guards have gone and will come back in h hours.

Koko can decide her bananas-per-hour eating speed of k. Each hour, she chooses some pile of bananas and eats k bananas from that pile. If the pile has less than k bananas, she eats all of them instead and will not eat any more bananas during this hour.

Koko likes to eat slowly but still wants to finish eating all the bananas before the guards return.

Return the minimum integer k such that she can eat all the bananas within h hours.

 

Example 1:

Input: piles = [3,6,7,11], h = 8
Output: 4

Example 2:

Input: piles = [30,11,23,4,20], h = 5
Output: 30

Example 3:

Input: piles = [30,11,23,4,20], h = 6
Output: 23

 

Constraints:

  • 1 <= piles.length <= 104
  • piles.length <= h <= 109
  • 1 <= piles[i] <= 109

Solutions

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class Solution:
    def minEatingSpeed(self, piles: List[int], h: int) -> int:
        # def checker(k: int) -> bool:
        #     return sum((val + k - 1) // k for val in piles) <= h

        # return bisect_left(range(1, max(piles) + 1), True, key=checker) + 1

        left, right = 1, max(piles)
        while left < right:
            k = (left + right) // 2

            hours_spent = 0
            for pile in piles:
                hours_spent += ceil(pile/k)

            if hours_spent <= h:
                right = k
            else:
                left = k + 1

        return left

Submission Stats:

  • Runtime: 164 ms (72.20%)
  • Memory: 20.6 MB (79.97%)