DEV Community

Abhishek Chaudhary
Abhishek Chaudhary

Posted on

1

Sort Even and Odd Indices Independently

You are given a 0-indexed integer array nums. Rearrange the values of nums according to the following rules:

  1. Sort the values at odd indices of nums in non-increasing order.
    • For example, if nums = [4,**1**,2,**3**] before this step, it becomes [4,**3**,2,**1**] after. The values at odd indices 1 and 3 are sorted in non-increasing order.
  2. Sort the values at even indices of nums in non-decreasing order.
    • For example, if nums = [**4**,1,**2**,3] before this step, it becomes [**2**,1,**4**,3] after. The values at even indices 0 and 2 are sorted in non-decreasing order.

Return the array formed after rearranging the values of nums.

Example 1:

Input: nums = [4,1,2,3]
Output: [2,3,4,1]
Explanation:
First, we sort the values present at odd indices (1 and 3) in non-increasing order.
So, nums changes from [4,1,2,3] to [4,3,2,1].
Next, we sort the values present at even indices (0 and 2) in non-decreasing order.
So, nums changes from [4,1,2,3] to [2,3,4,1].
Thus, the array formed after rearranging the values is [2,3,4,1].

Example 2:

Input: nums = [2,1]
Output: [2,1]
Explanation:
Since there is exactly one odd index and one even index, no rearrangement of values takes place.
The resultant array formed is [2,1], which is the same as the initial array.

Constraints:

  • 1 <= nums.length <= 100
  • 1 <= nums[i] <= 100

SOLUTION:

import heapq

class Solution:
    def sortEvenOdd(self, nums: List[int]) -> List[int]:
        n = len(nums)
        evens = []
        odds = []
        for i in range(n):
            if i & 1:
                heapq.heappush(odds, -nums[i])
            else:
                heapq.heappush(evens, nums[i])
        for i in range(n):
            if i & 1:
                nums[i] = -heapq.heappop(odds)
            else:
                nums[i] = heapq.heappop(evens)
        return nums
Enter fullscreen mode Exit fullscreen mode

Sentry image

See why 4M developers consider Sentry, “not bad.”

Fixing code doesn’t have to be the worst part of your day. Learn how Sentry can help.

Learn more

Top comments (0)

A Workflow Copilot. Tailored to You.

Pieces.app image

Our desktop app, with its intelligent copilot, streamlines coding by generating snippets, extracting code from screenshots, and accelerating problem-solving.

Read the docs

AWS GenAI LIVE!

GenAI LIVE! is a dynamic live-streamed show exploring how AWS and our partners are helping organizations unlock real value with generative AI.

Tune in to the full event

DEV is partnering to bring live events to the community. Join us or dismiss this billboard if you're not interested. ❤️