647.cpp

class Solution {
public:
    int countSubstrings(string s) {
        int ans = 0;
        for (int i = 0; i < s.length();i++) {
            ans += count(s, i, i);
            ans += count(s, i, i+1);
        }
        return ans;
    }
    int count(string& s, int l, int r) {
        int ans = 0;
        while(l >= 0 && r < s.length() && s[l--] == s[r++]) ++ans;
        return ans;
    }
};