Practice/Meta/Leetcode 2164. Sort Even and Odd Indices Independently

Leetcode 2164. Sort Even and Odd Indices Independently

CodingOptional

Problem

You are given a 0-indexed integer array nums. Your task is to rearrange the array using the following process:

1. Extract all elements at even indices (0, 2, 4, ...) and sort them in ascending order
2. Extract all elements at odd indices (1, 3, 5, ...) and sort them in descending order
3. Place the sorted even-indexed elements back into the even positions
4. Place the sorted odd-indexed elements back into the odd positions

Return the rearranged array.

Requirements

1. Elements at even indices must be sorted in non-decreasing (ascending) order
2. Elements at odd indices must be sorted in non-increasing (descending) order
3. The original index parity (even/odd) of each position must be preserved
4. Modify the array according to the sorting rules and return the result

Constraints

• 1 <= nums.length <= 100
• 1 <= nums[i] <= 100
• The array length can be either even or odd

Examples

Example 1:

` Input: nums = [4, 1, 2, 3] Output: [2, 3, 4, 1] Explanation:

• Even indices (0, 2): values [4, 2] → sorted ascending → [2, 4]
• Odd indices (1, 3): values [1, 3] → sorted descending → [3, 1]
• Reconstructed: [2, 3, 4, 1] `

Example 2:

` Input: nums = [2, 1] Output: [2, 1] Explanation:

• Even indices (0): values [2] → already sorted
• Odd indices (1): values [1] → already sorted
• Result: [2, 1] `

Example 3:

` Input: nums = [5, 4, 3, 4, 5, 2, 1, 6] Output: [1, 6, 3, 4, 5, 4, 5, 2] Explanation:

• Even indices: [5, 3, 5, 1] → [1, 3, 5, 5]
• Odd indices: [4, 4, 2, 6] → [6, 4, 4, 2]
• Merged back: [1, 6, 3, 4, 5, 4, 5, 2] `