When I submitted the below code, it got failed for one test case.

class Solution:
    def minEatingSpeed(self, piles: List[int], h: int) -> int:

        left,right = 1,max(piles)
        while left<=right:
            mid = (left+right)//2
            time = self.reqtime(piles,mid)
            if time==h:
                return mid
            elif time<h:
                right = mid-1
            else:
                left = mid+1
        return left
        
    
    def reqtime(self,arr,hourly):
        total = 0
        for i in arr:
            total += -(-i//hourly)
        return total

WRONG ANSWER 125 / 126 testcases passed

piles = [1,1,1,999999999]

h = 10

Output : 156250000

Expected : 142857143

But when I removed the code if time==h : return mid and replaced it with if time<=h : right=mid-1 in the below code, it worked fine!

class Solution:
    def minEatingSpeed(self, piles: List[int], h: int) -> int:

        left,right = 1,max(piles)
        while left<=right:
            mid = (left+right)//2
            time = self.reqtime(piles,mid)
            if time<=h:
                right = mid-1
            else:
                left = mid+1
        return left
        
    
    def reqtime(self,arr,hourly):
        total = 0
        for i in arr:
            total += -(-i//hourly)
        return total

Can someone explain why the first one doesn’t work? Because if time==h (h = maximum number of hours we have) , it means already k is the best case… If we increase the value of k , it will not be minimised. And if we decrease the value of k, it will cross the ‘h’ threshold.