<h2><a href="https://leetcode.com/problems/longest-palindromic-subsequence/">516. Longest Palindromic Subsequence</a></h2><h3>Medium</h3><hr><div><p>Given a string <code>s</code>, find <em>the longest palindromic <strong>subsequence</strong>'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 = "bbbab"
<strong>Output:</strong> 4
<strong>Explanation:</strong> One possible longest palindromic subsequence is "bbbb".
</pre>

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

<pre><strong>Input:</strong> s = "cbbd"
<strong>Output:</strong> 2
<strong>Explanation:</strong> One possible longest palindromic subsequence is "bb".
</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>
</div>