top of page

Palindromic Substrings

Given a string, your task is to count how many palindromic substrings in this string.

The substrings with different start indexes or end indexes are counted as different substrings even they consist of same characters.

Example 1:

Input: "abc"
Output: 3
Explanation: Three palindromic strings: "a", "b", "c".

Example 2:

Input: "aaa"
Output: 6
Explanation: Six palindromic strings: "a", "a", "a", "aa", "aa", "aaa".


  1. The input string length won't exceed 1000.


class Solution {public int countSubstrings(String s) {
        int result=0;
        for(int i=0;i<s.length();++i)
            result+=helper(s,i,i);   //odd length strings
            result+=helper(s,i,i+1);  //even length strings
        return result;
    private int helper(String s,int low, int high){
        int ans=0;
        while(low>=0 && high<s.length())
        return ans;

11 views0 comments

Recent Posts

See All

Minimum Deletions to Make Character Frequencies Unique

A string s is called good if there are no two different characters in s that have the same frequency. Given a string s, return the minimum number of characters you need to delete to make s good. The f

Smallest String With A Given Numeric Value

The numeric value of a lowercase character is defined as its position (1-indexed) in the alphabet, so the numeric value of a is 1, the numeric value of b is 2, the numeric value of c is 3, and so on.


bottom of page