<p>Given a string <code>s</code>, return <em>the longest</em> <span data-keyword="palindromic-string"><em>palindromic</em></span> <span data-keyword="substring-nonempty"><em>substring</em></span> in <code>s</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;babad&quot;
<strong>Output:</strong> &quot;bab&quot;
<strong>Explanation:</strong> &quot;aba&quot; is also a valid answer.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;cbbd&quot;
<strong>Output:</strong> &quot;bb&quot;
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= s.length &lt;= 1000</code></li>
	<li><code>s</code> consist of only digits and English letters.</li>
</ul>

class Solution:
    def longestPalindrome(self, s: str) -> str:
        #initiate odd palindrome tracking
        #initiate even palindrome tracking
        #things to track: left most pos, right most, the string
    
        palindromes = []
        max_len = 0
        longest = ''
        for i in range(len(s)):
            palindromes.append([s[i], i-1, i+1])
            if len(s[i]) > max_len:
                    max_len = len(s[i])
                    longest = s[i]
        for i in range(len(s)):
            if i + 1 < len(s):
                if s[i] == s[i+1]:
                    palindromes.append([s[i]+s[i+1], i-1, i+2])
                    if len(s[i]+s[i+1]) > max_len:
                        max_len = len(s[i]+s[i+1])
                        longest = s[i]+s[i+1]
        
        #while left exists and right exists and left = right
        #build the string, update pointers

        for anchor in palindromes:
            while anchor[1] >= 0 and anchor[2] < len(s) and s[anchor[1]] == s[anchor[2]]:
                anchor[0] = s[anchor[1]] + anchor[0] + s[anchor[2]]
                if len(anchor[0]) > max_len:
                    max_len = len(anchor[0])
                    longest = anchor[0]
                anchor[1] = anchor[1] - 1
                anchor[2] = anchor[2] + 1

        print(palindromes)

        return longest


        
        
20800