516. Longest Palindromic Subsequence
題目
Given a string s, find the longest palindromic subsequence's length in s.
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: s = "bbbab"
Output: 4
Explanation: One possible longest palindromic subsequence is "bbbb".
Example 2:
Input: s = "cbbd"
Output: 2
Explanation: One possible longest palindromic subsequence is "bb".
Constraints:
- 1 <= s.length <= 1000
- s consists only of lowercase English letters.
題目大意
給你一個字符串 s，找到 s 中最長的回文子串。