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];
}
}