516. Longest Palindromic Subsequence

来源：互联网发布：阿里巴巴淘宝便宜编辑：程序博客网时间：2024/06/05 15:11

516. Longest Palindromic Subsequence

题目描述：Given a string s, find the longest palindromic subsequence’s length in s. You may assume that the maximum length of s is 1000.
Example 1:
Input:

"bbbab"

Output:4

One possible longest palindromic subsequence is “bbbb”.

Example 2:
Input:

“cbbd”
Output: 2
One possible longest palindromic subsequence is “bb”.
题目大意：给定一个字符串，找出字符串中最长的回文子串

思路：DP dp[i][j]表示i到j范围最长的回文串状态转移方程

dp[i][j] = dp[i+1][j-1] + 2 if s.charAt(i) == s.charAt(j)otherwise, dp[i][j] = Math.max(dp[i+1][j], dp[i][j-1])

代码

package DP;/*** @author OovEver* 2017/12/25 11:03*/public class LeetCode516 {  public int longestPalindromeSubseq(String s) {//        dp[i][j]表示i到j范围最长的回文串//        dp[i][j] = dp[i+1][j-1] + 2 if s.charAt(i) == s.charAt(j)//        otherwise, dp[i][j] = Math.max(dp[i+1][j], dp[i][j-1])      int[][] dp = new int[s.length()][s.length()];      for(int i=s.length()-1;i>=0;i--) {          dp[i][i] = 1;          for(int j=i+1;j<s.length();j++) {              if (s.charAt(i) == s.charAt(j)) {                  dp[i][j] = dp[i + 1][j - 1] + 2;              } else {                  dp[i][j] = Math.max(dp[i + 1][j], dp[i][j - 1]);              }          }      }      return dp[0][s.length() - 1];  }}

阅读全文

'); })();