Competitive ProgrammingEasy

Wave Sort

Detailed guide and Python implementation for the 'Wave Sort' problem.

Problem Statement

Easy

Write a function wave_sort(arr) that takes an array of integers arr, sorts it in ascending order, and then swaps every adjacent pair of elements starting from index 0 (i.e., swap arr[0] and arr[1], then arr[2] and arr[3], and so on) to produce a wave-sorted array satisfying the property arr[0] >= arr[1] <= arr[2] >= arr[3] <= arr[4].... Return the resulting array.

Constraints
  • 1 <= len(arr) <= 10^5
  • -10^9 <= arr[i] <= 10^9

Examples

Example 1
Input
wave_sort([3, 6, 5, 10, 7, 20])
Output
[5, 3, 7, 6, 20, 10]
Explanation

First, sort the array to get [3, 5, 6, 7, 10, 20]. Swapping adjacent pairs: swap 3 and 5 -> [5, 3...], swap 6 and 7 -> [..., 7, 6...], swap 10 and 20 -> [..., 20, 10]. Result is [5, 3, 7, 6, 20, 10].

Example 2
Input
wave_sort([10, 90, 49, 2, 1, 5, 23])
Output
[2, 1, 10, 5, 49, 23, 90]
Explanation

Sort array to [1, 2, 5, 10, 23, 49, 90]. Swapping adjacent pairs gives [2, 1, 10, 5, 49, 23, 90].

Need a Hint?
Consider using Searching & Sorting-specific data structures like sets or heaps.
Edge Cases to Watch
  • Empty input structures
  • Single element inputs
  • Large numerical bounds

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