(647)Palindromic Substrings

class Solution {
public:
    void checkout(string &s , int &n , int left , int right , int &counter){
        while(left>=0 and right<n and s[left--]==s[right++])
            counter++;
    }
    int countSubstrings(string s) {
        int n = s.size();
        int counter = 0;
        for(int i=0 ; i<n ; i++){
            checkout(s,n,i,i,counter);
            checkout(s,n,i,i+1,counter);
        }
        return counter;
    }
};