Find the longest palindromic substring.

Updated Apr 28, 2026

Short answer

Expand around center or use DP to check all possible substrings.

Deep explanation

Intermediate string problems test your ability to use frequency maps and sliding windows. Expand around center or use DP to check all possible substrings.

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?

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