Introduction

In this blog post, we will explore how to solve the LeetCode problem "888" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

Alice and Bob have a different total number of candies. You are given two integer arrays aliceSizes and bobSizes where aliceSizes[i] is the number of candies of the ith box of candy that Alice has and bobSizes[j] is the number of candies of the jth box of candy that Bob has. Since they are friends, they would like to exchange one candy box each so that after the exchange, they both have the same total amount of candy. The total amount of candy a person has is the sum of the number of candies in each box they have. Return an integer array answer where answer[0] is the number of candies in the box that Alice must exchange, and answer[1] is the number of candies in the box that Bob must exchange. If there are multiple answers, you may return any one of them. It is guaranteed that at least one answer exists. Example 1: Input: aliceSizes = [1,1], bobSizes = [2,2] Output: [1,2] Example 2: Input: aliceSizes = [1,2], bobSizes = [2,3] Output: [1,2] Example 3: Input: aliceSizes = [2], bobSizes = [1,3] Output: [2,3] Constraints: 1 <= aliceSizes.length, bobSizes.length <= 104 1 <= aliceSizes[i], bobSizes[j] <= 105 Alice and Bob have a different total number of candies. There will be at least one valid answer for the given input.

Explanation

Here's a breakdown of the approach, followed by the Python code:

• Calculate the target sum: Determine the ideal sum each person should have after the exchange. This is achieved by calculating the total sum of Alice's and Bob's candies and dividing by 2.

• Utilize a set for efficient lookup: Store Bob's candy box sizes in a set. This allows for O(1) average-case time complexity when checking if Bob has a box that would satisfy the exchange condition.

• Iterate and find the exchange: Iterate through Alice's candy box sizes. For each box, calculate what Bob needs to give Alice to reach the target sum. Check if Bob possesses such a box using the set. If found, return the pair.

• Time & Space Complexity: Time: O(n + m), where n is the length of aliceSizes and m is the length of bobSizes. Space: O(m) due to the space used by the set containing Bob's sizes.

Code

    def fairCandySwap(aliceSizes, bobSizes):
    """
    Finds the candy box exchange that makes Alice and Bob have the same total amount of candy.

    Args:
        aliceSizes: A list of integers representing the sizes of Alice's candy boxes.
        bobSizes: A list of integers representing the sizes of Bob's candy boxes.

    Returns:
        A list of two integers representing the candy box sizes to be exchanged,
        where the first element is from Alice and the second is from Bob.
    """

    sum_alice = sum(aliceSizes)
    sum_bob = sum(bobSizes)

    target_sum = (sum_alice + sum_bob) // 2

    bob_sizes_set = set(bobSizes)

    for alice_size in aliceSizes:
        bob_size_needed = target_sum - (sum_alice - alice_size)
        if bob_size_needed in bob_sizes_set:
            return [alice_size, bob_size_needed]

    return []  # Should never happen, as a solution is guaranteed.