<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 {
public:
   int dp[1001][10001];
    int f(int i, int j, string&s, string&reverse) {
        
        if(i == s.size() or j == s.size()) return 0;

        if(dp[i][j]!=-1) return dp[i][j];
        int equal = -1e9, notequal = -1e9;
        if(s[i] == reverse[j]) {
            return dp[i][j] =  1 + f(i+1, j+1, s, reverse);
        } else {
             return dp[i][j] = max(f(i, j+1, s, reverse),f(i+1, j, s, reverse)); 
        }
    }
    int longestPalindromeSubseq(string s) {
        memset(dp, -1, sizeof(dp));
        string reverseString = s;
        reverse(reverseString.begin(), reverseString.end());
        //cout<<reverseString<<" "<<s;
        return f(0, 0, s, reverseString);
    }
};
52000