<p>Given a string <code>s</code>, find <em>the longest palindromic <strong>subsequence</strong>&#39;s length in</em> <code>s</code>.</p>

<p>A <strong>subsequence</strong> is a sequence that can be derived from another sequence by deleting some or no elements without changing the order of the remaining elements.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;bbbab&quot;
<strong>Output:</strong> 4
<strong>Explanation:</strong> One possible longest palindromic subsequence is &quot;bbbb&quot;.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;cbbd&quot;
<strong>Output:</strong> 2
<strong>Explanation:</strong> One possible longest palindromic subsequence is &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> consists only of lowercase English letters.</li>
</ul>

int dp[1001][1001];
class Solution {
public:
    int ans(int i,int j,string& s)
    {
        if(i>j)return 0;
        if(i==j)return 1;
        if(dp[i][j]!=-1)return dp[i][j];
        if(s[i]==s[j])
        return dp[i][j]=max({ans(i+1,j-1,s)+2,ans(i+1,j,s),ans(i,j-1,s)});
        return dp[i][j]=max({ans(i,j-1,s),ans(i+1,j,s)});
    }
    int longestPalindromeSubseq(string s) {
      
       int n=s.length();
       for(int i=0;i<n;i++)
       for(int j=0;j<n;j++)
       dp[i][j]=-1;
       return ans(0,n-1,s);
    }
};
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