Apple Redistribution into Boxes

Apple Redistribution into Boxes

What is this problem about?

The "Apple Redistribution into Boxes interview question" is a packing problem. You are given an array representing the number of apples in different packs and another array representing the capacities of various boxes. You want to take all the apples from all the packs and fit them into the minimum number of boxes possible.

Why is this asked in interviews?

Apple asks the "Apple Redistribution into Boxes coding problem" as a beginner-to-intermediate challenge to evaluate "Greedy interview pattern" skills. It tests if a candidate understands that to minimize the number of boxes, they should always fill the largest boxes first.

Algorithmic pattern used

This problem is solved using the Greedy and Sorting patterns.

1. Total Count: Calculate the sum of all apples in all packs.
2. Maximize Capacity: Sort the box capacities in descending order (largest to smallest).
3. Distribution: Subtract the capacity of the largest box from the total apple count. If apples remain, move to the next largest box.
4. Termination: Stop when the remaining apple count is zero or less.

Example explanation

Apples: [1, 3, 2] (Total = 6) Boxes: [4, 3, 1, 5]

1. Sort Boxes: [5, 4, 3, 1]
2. Box 1 (Size 5): $6 - 5 = 1$ apple left.
3. Box 2 (Size 4): $1 - 4 = -3$. All apples are packed. Result: 2 boxes.

Common mistakes candidates make

• Sorting apples: Spending time sorting the apple packs. It doesn't matter how the apples are packed initially; only the total count matters.
• Incorrect Sorting Order: Sorting boxes in ascending order, which would result in using more boxes than necessary.
• Off-by-one: Failing to count the final box that successfully takes the last few apples.

Interview preparation tip

Packing and scheduling problems are often greedy. If you need to "minimize" the count of containers, always try to use the largest ones first. This logic is simple but powerful and appears in many variations.