Sort elements only at even indices of an array, in python

Question

I have given the sample input and sample output.
The EVEN index is only sorted and the ODD index are left as it is.

Sample Input :

5
3 9 1 44 6

Sample Output :

1 9 3 44 6

Answer 1

You can assign a striding subscript with the sorted values of that same subscript:

arr = [3, 9, 1, 44, 6]

arr[::2] = sorted(arr[::2])  # assign even items with their sorted values

print(arr) # [1, 9, 3, 44, 6]

Answer 2

Here's what you can do using modified bubble sort technique:

def sortEvens(arr):
    arrLen = len(arr)
    for i in range(0, arrLen, 2):              # Jump by 2 units
        for j in range(0, arrLen-i-2, 2):      # Jump by 2 units
            if arr[j] > arr[j+2]:              # Comparing alternative elements
                temp = arr[j]
                arr[j] = arr[j+2]
                arr[j+2] = temp

    return arr


arr = [10, 45, 0, -34, 5, -899, 4]
print(sortEvens(arr))

# OUTPUT : [0, 45, 4, -34, 5, -899, 10]
positions-> 0  1   2   3   4    5    6