代码随想录day51

647.

/*
 * @lc app=leetcode.cn id=647 lang=cpp
 *
 * [647] 回文子串
 */

// @lc code=start
#include<iostream>
#include<vector>
#include<string>
using namespace std;
class Solution {
public:
    int countSubstrings(string s) {
        vector<vector<bool>> dp(s.size(), vector<bool>(s.size(), false));
        int res = 0;
        for (int i = 0; i < s.size(); i++) {
            dp[i][i] = true;
            res += 1;
        }
        for (int i = 0; i < s.size() - 1; i++) {
            if (s[i] == s[i + 1]) {
                dp[i][i + 1] = true;
                res += 1;
            }
        }
        for (int i = 2; i < s.size(); i++) {
            for (int j = 0; j < s.size() - i; j++) {
                if (s[j] == s[j + i] && dp[j + 1][j + i - 1]) {
                    dp[j][j + i] = true;
                    res += 1;
                }
            }
        }
        return res;
    }
};
// @lc code=end

 516.

/*
 * @lc app=leetcode.cn id=516 lang=cpp
 *
 * [516] 最长回文子序列
 */

// @lc code=start
#include<iostream>
#include<vector>
#include<string>
using namespace std;
class Solution {
public:
    int longestPalindromeSubseq(string s) {
        vector<vector<int>> dp(s.size(), vector<int>(s.size(), 0));
        for (int i = s.size() - 1; i >= 0; i--) {
            dp[i][i] = 1;
            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];
    }
};
// @lc code=end