<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:
    bool ispal(string a,int n){
        int s=0,e=n-1;
        while(e>s){
            if(a[s]!=a[e]){return false;}
            s++;e--;
        }
        return true;
    }
    string longestPalindrome(string s) {
        int n=s.length();
        string b="";
        for(int i=n-1;i>-1;i--){
            b+=s[i];
        }
        int dp[1005][1005];
        for(int i=0;i<n+1;i++){
            dp[i][0]=0;
        }
        for(int i=0;i<n+1;i++){
            dp[0][i]=0;
        }
        int p=0,in=0;
        string ans="";
        for(int i=1;i<n+1;i++){
            for(int j=1;j<n+1;j++){
                if(b[j-1]==s[i-1]){
                    dp[i][j]= 1 + dp[i-1][j-1];
                }
                else{
                    dp[i][j]=0;
                }
                if(dp[i][j]>p){
                    int t=dp[i][j];
                    string temp=s.substr(i-t,t);
                    if(ispal(temp,t)){ans=temp;p=dp[i][j];}
                }
            }
        }
        
        // cout<<dp[n][n]<<endl;
        return ans;

    }
};
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