Sort_even_and_odd_indeces_independently.py

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

# 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.
# 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. 

class Solution:
    def sortEvenOdd(self, nums: List[int]) -> List[int]:
        list_even = [nums[i] for i in range(len(nums)) if i%2 == 0]
        list_odd = [nums[i] for i in range(len(nums)) if i%2 != 0]
        
        list_even = sorted(list_even)
        list_odd = sorted(list_odd, reverse=True)
        
        tracker_even = 0
        tracker_odd = 0
        for i in range(len(nums)):
            if i%2 == 0:
                nums[i] = list_even[tracker_even]
                tracker_even += 1
            else:
                nums[i] = list_odd[tracker_odd]
                tracker_odd += 1
        
        return nums