Introduction

In this blog post, we will explore how to solve the LeetCode problem "747" 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

You are given an integer array nums where the largest integer is unique. Determine whether the largest element in the array is at least twice as much as every other number in the array. If it is, return the index of the largest element, or return -1 otherwise. Example 1: Input: nums = [3,6,1,0] Output: 1 Explanation: 6 is the largest integer. For every other number in the array x, 6 is at least twice as big as x. The index of value 6 is 1, so we return 1. Example 2: Input: nums = [1,2,3,4] Output: -1 Explanation: 4 is less than twice the value of 3, so we return -1. Constraints: 2 <= nums.length <= 50 0 <= nums[i] <= 100 The largest element in nums is unique.

Explanation

Here's an efficient solution to the problem:

• Find the Largest Element and its Index: Iterate through the array to find the largest element and its index.
• Check the Condition: Iterate through the array again and check if the largest element is at least twice as large as every other element.

• Return the Index or -1: If the condition is met, return the index of the largest element; otherwise, return -1.

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

• Space Complexity: O(1)

Code

    def dominantIndex(nums: list[int]) -> int:
    """
    Finds the index of the largest element in the array if it is at least twice as much as every other number in the array.

    Args:
        nums: An integer array where the largest integer is unique.

    Returns:
        The index of the largest element if it is at least twice as much as every other number in the array, or -1 otherwise.
    """
    largest = -1
    largest_index = -1

    for i, num in enumerate(nums):
        if num > largest:
            largest = num
            largest_index = i

    for num in nums:
        if num != largest and largest < 2 * num:
            return -1

    return largest_index