String Permutation Check Optimization | Dataford Interview Questions

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Problem

Airtel Digital processes short text values such as notification tokens and user-entered labels. Given two strings, determine whether the second string is a permutation of the first, meaning both contain exactly the same characters with the same frequencies, possibly in a different order.

Implement are_permutations(s, t) and optimize the solution for linear time complexity.

Formal Specification

Input: Two strings s and t containing only lowercase English letters (a through z).
Output: Return True if t is a permutation of s; otherwise, return False.
Character order does not matter, but character frequency does. For example, "aab" and "aba" are permutations, while "aab" and "abb" are not.

Constraints

0 <= len(s), len(t) <= 10^5
s and t contain only lowercase English letters
Return a boolean result
Target time complexity is O(n)

Function Signature

def are_permutations(s, t):