Description
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
Example 1:
Input:
Output:
One possible longest palindromic subsequence is “bbbb”.
Example 2:
Input:
Output:
One possible longest palindromic subsequence is “bb”.
Solution
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| class Solution {
public int longestPalindromeSubseq(String s) {
if (s.length() == 0) return 0;
int[][] dp = new int[s.length()][s.length()];
for (int i = 0; i < s.length(); i++)
dp[i][i] = 1;
for (int i = s.length() - 1; i >= 0; i--){
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];
}
}
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