代码随想录算法训练营第四六天| 647. 回文子串 516.最长回文子序列

今日任务

647. 回文子串

516.最长回文子序列

647. 回文子串

题目链接： . - 力扣（LeetCode）

class Solution {public int countSubstrings(String s) {int res = 0;boolean[][] dp = new boolean[s.length() + 1][s.length() + 1];for (int i = s.length() - 1; i >= 0; i--) {for (int j = i; j < s.length(); j++) {if (s.charAt(i) == s.charAt(j)){if (j - i <= 1) { dp[i][j] = true; res++;}else if (dp[i + 1][j - 1] == true) {dp[i][j] = true; res++;}}}}return res;}
}

516.最长回文子序列

题目链接：

class Solution {public int longestPalindromeSubseq(String s) {if (s.length() == 1) return 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][j - 1], dp[i + 1][j]);}}}return dp[0][s.length() - 1];}
}