MEDIUM NC#4 Blind #54 Arrays & Hashing
49. Group Anagrams
📖 Problem
Given an array of strings strs, group the anagrams together. You can return the answer in any order. An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.
🧠 Visual Learning Aid
1 Model the input into the right structure
2 Choose the core technique and invariant
3 Execute step-by-step with a sample
4 Validate complexity and edge cases
JS/TS Refreshers
- •Array methods (`push`, `pop`, `shift`, `slice`)
- •Object/Map/Set usage patterns
- •Function parameter and return typing
Logical Thinking Concepts
- •Define invariants before coding
- •Check edge cases first (`[]`, single element, duplicates)
- •Estimate time/space before implementation
💡 Approach
- → Anagrams have same sorted string representation
- → Use sorted string as hash map key
- → Group all strings with same key together
- → Time: O(n * k log k) where k is max string length
🧭 Prerequisites
🛠️ Hints & Pitfalls
Hints
- •Anagrams have same sorted string representation
- •Use sorted string as hash map key
- •Group all strings with same key together
Common Pitfalls
- •Time: O(n * k log k) where k is max string length
🧪 Test Cases
Hidden tests on submit: 2
Test Case 1
Not run Input:
groupAnagrams(["eat","tea","tan","ate","nat","bat"]); Expected:
[["eat","tea","ate"], ["tan","nat"], ["bat"]] Test Case 2
Not run Input:
groupAnagrams([""]); Expected:
[[""]] Test Case 3
Not run Input:
groupAnagrams(["a"]); Expected:
[["a"]] 📝 Code Editor
📤 Output