Introduction

In this blog post, we will explore how to solve the LeetCode problem "1313" 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 are given a list nums of integers representing a list compressed with run-length encoding. Consider each adjacent pair of elements [freq, val] = [nums[2i], nums[2i+1]] (with i >= 0). For each such pair, there are freq elements with value val concatenated in a sublist. Concatenate all the sublists from left to right to generate the decompressed list. Return the decompressed list. Example 1: Input: nums = [1,2,3,4] Output: [2,4,4,4] Explanation: The first pair [1,2] means we have freq = 1 and val = 2 so we generate the array [2]. The second pair [3,4] means we have freq = 3 and val = 4 so we generate [4,4,4]. At the end the concatenation [2] + [4,4,4] is [2,4,4,4]. Example 2: Input: nums = [1,1,2,3] Output: [1,3,3] Constraints: 2 <= nums.length <= 100 nums.length % 2 == 0 1 <= nums[i] <= 100

Explanation

• Iterate through the input list nums in pairs.
  • For each pair [freq, val], create a sublist containing freq copies of val.
  • Concatenate all the sublists to generate the final decompressed list.

• Runtime Complexity: O(n), where n is the length of the output list. Storage Complexity: O(n), where n is the length of the output list.

Code

    def decompress_rl_elist(nums):
    """
    Decompresses a list encoded with run-length encoding.

    Args:
        nums: A list of integers representing the compressed list.

    Returns:
        A list of integers representing the decompressed list.
    """
    decompressed_list = []
    for i in range(0, len(nums), 2):
        freq = nums[i]
        val = nums[i + 1]
        decompressed_list.extend([val] * freq)
    return decompressed_list