Permutation Check for Two Strings | Dataford Interview Questions

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Problem

A PlayStation system may compare two user-entered strings, such as a profile label and a reordered version of it. Given two strings, determine whether one is a permutation of the other.

Two strings are permutations if they contain exactly the same characters with the same frequencies, regardless of order. The comparison is case-sensitive, and spaces and punctuation count as characters.

Formal Specification

Implement are_permutations(s, t):

Input: two strings s and t.
Output: return True if t is a permutation of s; otherwise return False.
Do not modify either input string.

Aim for an O(n) solution using a character-frequency data structure rather than sorting. Let n be the length of the longer input string.

Constraints

0 <= len(s), len(t) <= 10^5
Strings may contain Unicode characters
Comparisons are case-sensitive
Whitespace and punctuation are significant

Function Signature

def are_permutations(s, t):