Introduction

In this blog post, we will explore how to solve the LeetCode problem "2441" 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

Given an integer array nums that does not contain any zeros, find the largest positive integer k such that -k also exists in the array. Return the positive integer k. If there is no such integer, return -1. Example 1: Input: nums = [-1,2,-3,3] Output: 3 Explanation: 3 is the only valid k we can find in the array. Example 2: Input: nums = [-1,10,6,7,-7,1] Output: 7 Explanation: Both 1 and 7 have their corresponding negative values in the array. 7 has a larger value. Example 3: Input: nums = [-10,8,6,7,-2,-3] Output: -1 Explanation: There is no a single valid k, we return -1. Constraints: 1 <= nums.length <= 1000 -1000 <= nums[i] <= 1000 nums[i] != 0

Explanation

Here's the breakdown of the solution and the Python code:

• Approach:

  • Use a set to efficiently check for the existence of the negative counterpart of each positive number.
  • Iterate through the array, and for each positive number, check if its negative exists in the set.
  • Keep track of the largest 'k' found so far.

• Complexity:

  • Runtime: O(n), where n is the length of the input array.
  • Storage: O(n) in the worst case, to store all elements in the set.

Code

    def find_max_k(nums: list[int]) -> int:
    """
    Given an integer array nums that does not contain any zeros, find the largest positive integer k such that -k also exists in the array.
    Return the positive integer k. If there is no such integer, return -1.
    """
    num_set = set(nums)
    max_k = -1

    for num in nums:
        if num > 0 and -num in num_set:
            max_k = max(max_k, num)

    return max_k