class Solution {
public:
    string& trim(std::string &s) 
    {
        if (s.empty()) 
        {
            return s;
        }

        s.erase(0,s.find_first_not_of(" "));
        s.erase(s.find_last_not_of(" ") + 1);
        return s;
    }
    int strToInt(string str) {
        str = trim(str);
        if(str.size() == 0)
        return 0;
        int res = 0;
        int maxint = INT_MAX/10;
        int i = 1;
        int flag = 1;
        if(str[0] == '-')
        flag = -1;
        else if(str[0] != '+')
        i = 0;
        for(int j=i;j<str.size();j++)
        {
            if(str[j] < '0' || str[j] > '9')
            break;
            if(res > maxint || res == maxint && str[j]>'7')
            return flag == 1 ? INT_MAX : INT_MIN;
            res = res * 10 + (str[j] - '0');
        }

        return res * flag;
    }
};