Palindromic Substrings

Med
Code
Loading editor...
Tap Analyze to see visualization
Variables

Run code to see variables

Output

Console output will appear here

Press Space to start to step? all shortcuts

Solution Guide: Palindromic Substrings

Approach

Treat each index (and gap between indices) as a palindrome center, then expand while characters match.

Complexity Analysis

Time
O(n^2)
Space
O(1)

Pattern

Expand Around Center

Why It Works

Every palindrome has a unique center, so enumerating all centers counts all palindromic substrings exactly once.

Updated Feb 2026