<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 {
public:
    string longestPalindrome(string s) {
        string maxString=s.substr(0, 1);
        for (int i=1; i<s.size()-maxString.size()/2; i++){
            int j=1;
            if (s[i-1]==s[i]){
                string subEven=s.substr(i-1, 2);
                while (i-1-j>=0 && i+j<s.size()){
                    if (s[i-1-j]==s[i+j]){
                        subEven=s.substr(i-j-1, 2*j+2);
                    }
                    else{
                        break;
                    }
                    j++;
                }
                if (subEven.size()>maxString.size())
                    maxString=subEven;
            }
            j=1;
            string subOdd=s.substr(i, 1);
            while (i-j>=0 && i+j<s.size()){
                if (s[i-j]==s[i+j]){
                    subOdd=s.substr(i-j, 2*j+1);
                }
                else{
                    break;
                }
                j++;
            }
            if (subOdd.size()>maxString.size())
                maxString=subOdd;
        }
        return maxString;
    }
};
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