Leetcode647. Palindrome substring

#include <string>
#include <iostream>

class Solution {
public:
    int countSubstrings(std::string s) 
    {
        int ret = 0;
        if (s.empty() || s.length() <= 0)
        {
            return ret;
        }
        for (int i = 0; i < s.length(); i++)
        {
            for (int j = i + 1; j < s.length(); j++)
            {
                if (strIsPalindrome(s.substr(i, j - i + 1)))
                {
                    ret++;
                }
            }
            
        }
        return ret + s.length();
    }
    //  Determine whether the string is a palindrome 
    bool strIsPalindrome(const std::string& str)
    {
        int begin = 0;
        int end = str.length() - 1;
        while (begin < end)
        {
            if (str[begin] == str[end])
            {
                begin++;
                end--;
            }
            else
            {
                return false;
            }
        }
        return true;
    }
};

int main()
{
    Solution solution;
    std::cout << solution.countSubstrings("abc") << std::endl;
    std::cout << solution.countSubstrings("aaa") << std::endl;
    return 0;
}