Introduction

In this blog post, we will explore how to solve the LeetCode problem "3392" 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, return the number of subarrays of length 3 such that the sum of the first and third numbers equals exactly half of the second number. Example 1: Input: nums = [1,2,1,4,1] Output: 1 Explanation: Only the subarray [1,4,1] contains exactly 3 elements where the sum of the first and third numbers equals half the middle number. Example 2: Input: nums = [1,1,1] Output: 0 Explanation: [1,1,1] is the only subarray of length 3. However, its first and third numbers do not add to half the middle number. Constraints: 3 <= nums.length <= 100 -100 <= nums[i] <= 100

Explanation

Here's the breakdown of the solution:

• Iterate through subarrays of length 3: The core idea is to examine each possible subarray of length 3 within the given array.
• Check the condition: For each subarray, verify if the sum of the first and third elements is equal to half of the second element.

• Count valid subarrays: Increment a counter each time the condition is met.

• Runtime Complexity: O(n), where n is the length of the input array. Storage Complexity: O(1).

Code

    def count_subarrays(nums):
    """
    Counts the number of subarrays of length 3 where the sum of the first and third
    numbers equals half of the second number.

    Args:
        nums: A list of integers.

    Returns:
        The number of subarrays that satisfy the condition.
    """
    count = 0
    for i in range(len(nums) - 2):
        if nums[i] + nums[i + 2] == nums[i + 1] / 2:
            count += 1
    return count