Navigating the Loop: Advanced Tips

This approach beautifully sidesteps non-alphabetical characters. But let's talk about the "how" for a moment. To ensure accuracy, remember to iterate the reversedAlpha array independently from the loop that scans the original string.

Optional: Simplifying with .shift()

If the thought of juggling another pointer or index leaves you dizzy, here's a simpler alternative: use the .shift() method. This function efficiently grabs the left-most element in an array, essentially doing the pointer's job for you. Imagine it as having a helper who hands you each reversed "gold coin" as you walk along your original path.

Method 2: The Two-Pointer Skip Technique

Method 2

Dual Pointers with a Twist

The second approach also involves using two pointers, much like our first method. However, this one comes with a twist: it skips over the non-alphabetical characters directly.

How to Skip Efficiently

Just like in a dance, when a couple realizes they are out of sync, they adjust their steps. Similarly, if either of the pointers encounters a non-alphabetical character, it simply "dances" past it, without making a swap.

By adopting this approach, you get to keep the original sequence of non-alphabetical characters intact while reversing only the alphabets. Think of it as flipping some tiles on a mosaic floor without disturbing the overall pattern.

1import re
2
3def swap(arr, a, b):
4    temp = arr[a]
5    arr[a] = arr[b]
6    arr[b] = temp
7    return arr
8
9
10def reverse_only_alpha(s):
11    start = 0
12    end = len(s) - 1
13    arr = list(s)
14
15    r = re.compile("[a-zA-Z]")
16
17    while start <= end:
18        if not r.match(arr[start]):
19            start += 1
20        elif not r.match(arr[end]):
21            end -= 1
22        else:
23            swap(arr, start, end)
24            start += 1
25            end -= 1
26
27    return "".join(arr)
28
29print(reverse_only_alpha("sea!$hells3"))