Basic String and Array Coding | Dataford Interview Questions

Your question is Basic String and Array Coding. Start with the requirements on the right.

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Problem

While validating text and numeric fields in a PTC application, implement one function that reverses a string, counts the frequency of each letter, and swaps two integers without using a third variable.

Formal Specification

Implement process_text_and_swap(text, a, b):

Return the reversed string.
Count alphabetic characters only. Treat uppercase and lowercase letters as the same, and store frequency keys in lowercase. Ignore spaces, digits, punctuation, and other non-letter characters.
Swap a and b without declaring or using a third variable.
Return a dictionary with keys reversed, frequencies, swapped_a, and swapped_b.

The frequencies value must be a dictionary. The order of its keys does not affect correctness.

Constraints

0 <= len(text) <= 10^5
Count only characters for which isalpha() returns True.
Frequency keys must be lowercase.
-10^9 <= a, b <= 10^9
The integer swap must not use a third variable.

Function Signature

def process_text_and_swap(text, a, b):