Given a string s, return the longestpalindromicsubstring in s.
Example 1:
Input: s = "babad"
Output: "bab"
Explanation: "aba" is also a valid answer.
Example 2:
Input: s = "cbbd"
Output: "bb"
Pseudocode
- use a function that is able to extend outwards to compare chars
- in a for loop, use function to cover both odd and even cases
- e.g. for loop travels to middle of string and finds two palindrome char
- function extends outwards to assess how long this palindrome is
- store start and end position of longest palindrome
- return substring with starting and ending index
Solution
// from solution - does the same thing
var longestPalindrome = function (s) {
const len = s.length;
let start = 0;
let end = 0;
function extendPalindrome(str, e) {
while (str >= 0 && e < len && s[str] === s[e]) {
if (e - str > end - start) [start, end] = [str, e];
str--;
e++;
}
}
for (let i = 0; i < len; i++) {
extendPalindrome(i, i); // for odd length
extendPalindrome(i, i + 1); // for even length
}
return s.slice(start, end + 1);
};
