Coding: Duplicate Characters with HashMap | Dataford Interview Questions

How do you identify duplicate characters in a string using a HashMap? Treat uppercase and lowercase versions of a letter as the same character, preserve the original spelling, and return each distinct duplicated form in first-appearance order. Implement def find_duplicate_characters(s):, returning a list of characters; for example, "TBOtek" returns ["T", "t"].

Constraints

0 <= len(s) <= 10^4
s contains ASCII letters, digits, spaces, or punctuation
Duplicate matching is case-insensitive
Return each distinct original character at most once
Results must follow first-appearance order

Function Signature

def find_duplicate_characters(s):

Your question is Coding: Duplicate Characters with HashMap. Start with the requirements in the Question tab.

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Problem

Constraints

0 <= len(s) <= 10^4
s contains ASCII letters, digits, spaces, or punctuation
Duplicate matching is case-insensitive
Return each distinct original character at most once
Results must follow first-appearance order

Function Signature

def find_duplicate_characters(s):

Your question is Coding: Duplicate Characters with HashMap. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.