Longest Palindromic Subsequence
Problem Statement
Given a sequence, find the length of its Longest Palindromic Subsequence (LPS). In a palindromic subsequence, elements read the same backward and forward.
A subsequence is a sequence that can be derived from another sequence by deleting some or no elements without changing the order of the remaining elements.
Example 1:
Input: "abdbca"
Output: 5
Explanation: LPS is "abdba".
Example 2:
Input: = "cddpd"
Output: 3
Explanation: LPS is "ddd".
Example 3:
Input: = "pqr"
Output: 1
Explanation: LPS could be "p", "q" or "r".
Constraints:
1 <= st.length <= 1000syconsists only of lowercase English letters.
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