Introduction

In this blog post, we will explore how to solve the LeetCode problem "976" 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 largest perimeter of a triangle with a non-zero area, formed from three of these lengths. If it is impossible to form any triangle of a non-zero area, return 0. Example 1: Input: nums = [2,1,2] Output: 5 Explanation: You can form a triangle with three side lengths: 1, 2, and 2. Example 2: Input: nums = [1,2,1,10] Output: 0 Explanation: You cannot use the side lengths 1, 1, and 2 to form a triangle. You cannot use the side lengths 1, 1, and 10 to form a triangle. You cannot use the side lengths 1, 2, and 10 to form a triangle. As we cannot use any three side lengths to form a triangle of non-zero area, we return 0. Constraints: 3 <= nums.length <= 104 1 <= nums[i] <= 106

Explanation

• Triangle Inequality Theorem: The sum of the lengths of any two sides of a triangle must be greater than the length of the third side. We use this principle to determine if a triangle can be formed.
  • Sorting for Efficiency: Sort the array in descending order. This allows us to efficiently check the largest possible side lengths first. If nums[i] + nums[i+1] > nums[i+2] is true, we found the largest possible triangle perimeter and no further searching is required.
  • Iterate and Check: Iterate through the sorted array, checking if the triangle inequality holds for consecutive triplets of side lengths.

• Runtime Complexity: O(n log n) due to sorting. Storage Complexity: O(1) excluding the input array (in-place sort is possible).

Code

    def largestPerimeter(nums):
    """
    Given an integer array nums, return the largest perimeter of a triangle
    with a non-zero area, formed from three of these lengths.
    If it is impossible to form any triangle of a non-zero area, return 0.
    """
    nums.sort(reverse=True)
    for i in range(len(nums) - 2):
        if nums[i] < nums[i + 1] + nums[i + 2]:
            return nums[i] + nums[i + 1] + nums[i + 2]
    return 0