🎮 Hash Maps (Practice)

Companion to the Hash Maps & Sets guide. Use a hash map to turn an O(n²) scan into a single O(n) pass. Edit and run the code right here — it executes in your browser.

🐍 Your turn

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🧠 Challenge yourself

1. Group a list of words into anagrams using a hash map.
2. Find the first non-repeating character in a string.
3. Why is average lookup O(1) but worst case O(n)?

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Continue the learning path → Linked Lists