<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];
string s,t;
int rec(int i,int j){

    if(i< 0 || j < 0) return 0;
    if(dp[i][j]!=-1) return dp[i][j];

    int ans = 0;
    if(s[i]==t[j]){
        ans = max(ans,1 + rec(i-1,j-1));
    }
    ans = max({ans,rec(i,j-1),rec(i-1,j)});

    return dp[i][j]=ans;
}
class Solution {
public:
    int longestPalindromeSubseq(string p) {
        s = p;
        reverse(p.begin(),p.end());
        t = p;
        memset(dp,-1,sizeof(dp));
        int n = s.size();
        return rec(n-1,n-1);
    }
};
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