<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 maxStr = "";
        for(int i = 0 ; i < s.size(); i++){
            string longestPalCenteredAtI = longestPalindromeCenteredHere(s,i);
            maxStr = longestPalCenteredAtI.size() > maxStr.size() ? longestPalCenteredAtI : maxStr;
        }
        return maxStr;
    }

    string longestPalindromeCenteredHereOdd(string s, int centerPt){
        int l = centerPt;
        int r = centerPt;
        while(l >= 0 && r < s.size() && s[l] == s[r]){
            l--;
            r++;
        }
        l++;
        r--;
        return s.substr(l, r - l + 1);
    }

    string longestPalindromeCenteredHereEven(string s, int centerPt){
        int l = centerPt;
        int r = centerPt + 1;
        while(l >= 0 && r < s.size() && s[l] == s[r]){
            l--;
            r++;
        }
        l++;
        r--;
        return s.substr(l, r - l + 1);
    }

    string longestPalindromeCenteredHere(string s, int centerPt){
        string odd = longestPalindromeCenteredHereOdd(s, centerPt);
        string even = longestPalindromeCenteredHereEven(s, centerPt);
        return odd.size() > even.size() ? odd : even;
    }
};
258919