<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>

class Solution {
    int dp[1001][1001];
    int solve(string &s, string &s1,int index1,int index2){
        if(index1 >= s.size() || index2 >= s1.size()){
            return 0;
        }
        if(dp[index1][index2]!=-1) return dp[index1][index2];
        int a = INT_MIN;
        if(s[index1]==s1[index2]){
            a = 1+ solve(s,s1,index1+1,index2+1);
        }
        int b = solve(s,s1,index1+1,index2);
        int c = solve(s,s1,index1,index2+1);


        return dp[index1][index2]=max({a,b,c});
    }
public:
    int longestPalindromeSubseq(string s) {
        string s1 = s;
        reverse(s1.begin(),s1.end());
        memset(dp,-1,sizeof(dp));
        return solve(s,s1,0,0);
        
    }
};
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