Palindromic Substrings
Given a string s, return how many of its substrings are palindromes. A substring is a contiguous run of characters, and substrings at different positions are counted separately even when their text is the same.
For example "aaa" has six palindromic substrings: three of length 1, two of length 2 and one of length 3.
Constraints
1 <= s.length <= 1000sconsists of lowercase English letters.
Examples
Example 1
Input: s = "abc" Output: 3
Only the three single letters are palindromes.
Example 2
Input: s = "aaa" Output: 6
Six substrings: a (three times), aa (twice) and aaa.
Example 3
Input: s = "abba" Output: 6
a, b, b, a, then "bb" and "abba": 6.
JavaScript you'll use: Strings and characters
/**
* @param {string} s
* @return {number}
*/
function countSubstrings(s) {
}
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