<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:
        if s == "":
            return 0
        n = len(s)
        isPali = [[False] * n for _ in range(n)]
        for i in range(n):
            isPali[i][i] = True

        max_l, max_i = 1,0
        for end in range(n):
            print(max_l)
            for start in range(end-1, -1, -1):
                if s[start] == s[end]:
                    if end - start == 1 or isPali[start+1][end-1]:
                        isPali[start][end] = True
                        l = end - start + 1
                        if l > max_l:
                            max_l = l
                            max_i = start

        return s[max_i:max_i+max_l] 
                    
                    
        return 


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