Introduction

In this blog post, we will explore how to solve the LeetCode problem "2640" 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

We define the conversion array conver of an array arr as follows: conver[i] = arr[i] + max(arr[0..i]) where max(arr[0..i]) is the maximum value of arr[j] over 0 <= j <= i. We also define the score of an array arr as the sum of the values of the conversion array of arr. Given a 0-indexed integer array nums of length n, return an array ans of length n where ans[i] is the score of the prefix nums[0..i]. Example 1: Input: nums = [2,3,7,5,10] Output: [4,10,24,36,56] Explanation: For the prefix [2], the conversion array is [4] hence the score is 4 For the prefix [2, 3], the conversion array is [4, 6] hence the score is 10 For the prefix [2, 3, 7], the conversion array is [4, 6, 14] hence the score is 24 For the prefix [2, 3, 7, 5], the conversion array is [4, 6, 14, 12] hence the score is 36 For the prefix [2, 3, 7, 5, 10], the conversion array is [4, 6, 14, 12, 20] hence the score is 56 Example 2: Input: nums = [1,1,2,4,8,16] Output: [2,4,8,16,32,64] Explanation: For the prefix [1], the conversion array is [2] hence the score is 2 For the prefix [1, 1], the conversion array is [2, 2] hence the score is 4 For the prefix [1, 1, 2], the conversion array is [2, 2, 4] hence the score is 8 For the prefix [1, 1, 2, 4], the conversion array is [2, 2, 4, 8] hence the score is 16 For the prefix [1, 1, 2, 4, 8], the conversion array is [2, 2, 4, 8, 16] hence the score is 32 For the prefix [1, 1, 2, 4, 8, 16], the conversion array is [2, 2, 4, 8, 16, 32] hence the score is 64 Constraints: 1 <= nums.length <= 105 1 <= nums[i] <= 109

Explanation

Here's the breakdown of the solution:

• Iterative Prefix Calculation: Iterate through the input array nums, considering each prefix nums[0...i].
• Maintain Maximum: In each iteration, keep track of the maximum element encountered so far within the prefix.

• Efficient Score Calculation: Calculate the conversion array score on the fly by adding each converted element to an accumulator.

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

• Storage Complexity: O(n) to store the result array.

Code

    def conversion_array_score(nums):
    n = len(nums)
    ans = [0] * n
    max_so_far = 0
    current_score = 0

    for i in range(n):
        max_so_far = max(max_so_far, nums[i])
        converted_value = nums[i] + max_so_far
        current_score += converted_value
        ans[i] = current_score

    return ans