<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 s1=s;
        reverse(s.begin(),s.end()); 
        string ans;
       int n=s.size();
        int res=0;
      int dp[n+1][n+1];
        for(int i=0;i<=n;i++){
            for(int j=0;j<=n;j++){
                if(i==0||j==0)
                    dp[i][j]=0;
               else if(s[i-1]==s1[j-1]){
                    dp[i][j]=dp[i-1][j-1]+1;
                   
                   
                }
                else
                    dp[i][j]=0;
                
                 if(dp[i][j]>res)
                    {
                        string temp=s.substr(i-dp[i][j],dp[i][j]);
                        string rev=temp;
                        reverse(rev.begin(),rev.end());
                        if(temp==rev){    
                             ans=temp;
                        res=dp[i][j];
                        }
                           
                    }
            }
            
        }
        return ans;
    }
};
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