CodingMediumcod-g150

Subject PalindromesLevel Mid–Senior~20 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Return the number of palindromic substrings of s, counting substrings at different positions separately even if they are equal as strings. Single characters count, so "aaa" has 6 palindromic substrings: a, a, a, aa, aa, aaa. The string can be a few thousand characters; an O(n^2) expand-around-center solution is expected.

Implement

count_palindromic_substrings(s: str) → int

Examples

in["aaa"]out6

What a strong answer looks like

State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.

Learn the concepts

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.