Solution to Pick Peak problem on Codewars

Codewars is an interesting website for enhancing your coding skills. I have been playing around with the site for a while trying to get better at Python. I came across the “Pick Peak” problem on codewars that I found very interesting. In this post I’ll take you guys through the Solution to Pick Peak problem on Codewars. The ‘Pick Peak’ problem was fun and interesting. Here’s the problem.


In this kata, you will write a function that returns the positions and the values of the “peaks” (or local maxima) of a numeric array.

For example, the array arr = [0, 1, 2, 5, 1, 0] has a peak in position 3 with a value of 5 (arr[3] equals 5).

The output will be returned as a struct (PosPeaks) with two properties: Pos and Peaks. Both of these properties should be arrays. If there is no peak in the given array, then the output should be {Pos: [], Peaks: []}.

Example: PickPeaks([3, 2, 3, 6, 4, 1, 2, 3, 2, 1, 2, 3]) returns {Pos: [3, 7], Peaks: [6, 3]}

All input arrays will be valid numeric arrays (although it could still be empty), so you won’t need to validate the input.

The first and last elements of the array will not be considered as peaks (in the context of a mathematical function, we don’t know what is after and before and therefore, we don’t know if it is a peak or not).

Also, beware of plateaus! [1, 2 , 2 , 2 , 1] has a peak while [1, 2, 2, 2, 3] does not. In case of a plateau-peak, please only return the position and value of the beginning of the plateau. For example: PickPeaks([1, 2, 2, 2, 1]) returns {Pos: [1], Peaks: [2]}

Have fun!

Here’s my solution to it in Python. It reads a bit like C though!

def pick_peaks(arr):
    prev, cur = 0, 0
    pos = []
    peaks = []

    for next in range(1, len(arr)):
        if arr[next] > arr[cur]:
            prev = cur
            cur = next
          if arr[next] < arr[cur]:
              if arr[prev] < arr[cur]:
              prev = cur
              cur = next

    return {"pos": pos, "peaks": peaks}

For more solutions, follow the codewars, puzzles or solutions tag.


Senior Software Engineer @ Apple | ex-Yahoo Finance Eng | Distributed Computing @ Georgia Tech | Python, Java | Scalability, ML/AI, C* | 🇮🇳 | Opinions mine only

Also published on Medium.

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