代码随想录60期day50

647. Palindromic Substrings

class Solution {
public:
    int countSubstrings(string s) {
        vector<vector<bool>>dp(s.size(),vector<bool>(s.size(),false));
        int result = 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){
        				result++;
        				dp[i][j]= true;
        			}else if(dp[i+1][j-1]){
        				result++;
        				dp[i][j] = true;
        			}
        		}
        	}
        }
        return result;
    }
};

516

class Solution {
public:
    int longestPalindromeSubseq(string s) {
        vector<vector<int>>dp(s.size(),vector<int>(s.size(),0));
        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];
    }
};