midStrings
Find the first non-repeating character in a string.
Updated Apr 28, 2026
Short answer
Use a frequency map (Hash Table) to count occurrences and scan the string.
Deep explanation
Intermediate string problems test your ability to use frequency maps and sliding windows. Use a frequency map (Hash Table) to count occurrences and scan the string.
Real-world example
Search filters that ignore character order.
Common mistakes
- Inefficiently sorting strings for an anagram check when a frequency map is O(n).
Follow-up questions
- What is the time complexity of sorting?