<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) {
        int n = s.size();
        string res = "";

        for(int i = 0; i < n; i++) {
            string cur(1,s[i]);
            int l = i-1;
            int r = i+1;

            while(l >= 0 && r < n && s[l] == s[r]) {
                cur = s[l] + cur + s[r];
                l--;
                r++;
            }

            l = i;
            r = i + 1;
            while (l >= 0 && r < n && s[l] == s[r]) {
                if (r - l + 1 > res.size()) {
                    res = s.substr(l, r - l + 1);
                }
                l--;
                r++;
            }

            if(cur.size() > res.size()) {
                res = cur;
            }
        }

        return res;
    }
};
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