class Solution {
public:
int countSubstrings(string s) {
vector<vector<bool>> dp(s.size(), vector<bool>(s.size(), false));
int reslut = 0;
for(int i = s.size() - 1;i >= 0;i--) {
for(int j = i;j < s.size();j++) {
if(s[i] == s[j]) {
if(j - i <= 1) {
dp[i][j] = true;
reslut++;
} else {
if(dp[i + 1][j - 1]) {
reslut++;
dp[i][j] = true;
}
}
}
}
}
return reslut;
}
};
题目2:516. 最长回文子序列 - 力扣(LeetCode)
class Solution {
public:
int longestPalindromeSubseq(string s) {
vector<vector<int>> dp(s.size(), vector<int>(s.size()));
for(int i = 0;i < s.size();i++) dp[i][i] = 1;
for(int i = s.size() - 1;i >= 0;i--) {
for(int j = i + 1;j < s.size();j++) {
if(s[i] == s[j]) {
dp[i][j] = dp[i + 1][j - 1] + 2;
}else {
dp[i][j] = max(dp[i + 1][j], dp[i][j - 1]);
}
}
}
return dp[0][s.size() - 1];
}
};