int palindromeIndex(string s) {
    size_t left{}, right{s.size() - 1};
		// last occurrence 
    std::pair<int, int> index{};
    int cursor{-1};
		// track direction pointer is moving in case of char mismatch
		// 0: left++
		// 1: right--
		// 2: no solution found left-right 
    size_t counter{};
    while(left < right)
    {
        if(s[left] == s[right])
        {
            left++;
            right--;
        }
        else {
            if(counter >= 2)
                return -1;
            else if(counter == 1)
            {
                left = index.first;
                right = index.second;
                cursor = right;
                right--;        
            }
            else {
                index = {left, right};
                cursor = left;
                left++;
            }
            counter++;
        }
    }
        
    return cursor;
}