<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:
        a=[[1]]
        idx=0
        max_=1

        for i in range(1,len(s)):
            temp=a[i-1]
            best=[1]
            for j in temp:
                if (i-j-1>=0 and s[i-j-1]==s[i]):
                    best.append(j+2)
                    if (j+2>max_):
                        max_=j+2
                        idx=i

            if (s[i-1]==s[i]):
                k=i-1
                while (k>=0 and s[k]==s[i]):
                    k-=1
                best.append(i-k)
                if (i-k>max_):
                    max_=i-k
                    idx=i
            a.append(best)
            
        return s[idx-max_+1:idx+1]



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