8. String to Integer (atoi)

class Solution {
public:
    int myAtoi(string_view s)
    {
        int index = 0, ans = 0, d = 0;

        const int size = int(s.size()); 

        while(index < size && s[index] == ' ')
        { 
            ++index;
        }
        
        if(index == size)
        {
            return 0;
        }

        int sign = 1;
        
        if(s[index] == '-')
        {
            sign = -1;
            ++index;
        }
        else if(s[index] == '+')
        {
            ++index;
        }

        while(index < size && '0' <= s[index] && s[index] <= '9')
        {
            d = int(s[index] - '0');
            
            if(ans < INT_MAX / 10 || ans == INT_MAX / 10 && d <= INT_MAX % 10)
            {
                ans = ans * 10 + d;    
            }
            else
            {
                return sign >= 0 ? INT_MAX : INT_MIN;
            }

            ++index;
        }

        return ans * sign;    
    }

    int myAtoi1(string_view s) 
    {
         int index = 0, ans = 0, d = 0;

        const int size = int(s.size()); 

        for(; index < size && s[index] == ' '; ++index);

        if(index == size)
        {
            return 0;
        }

        if(s[index] == '-')
        {
            while(++index < size && '0' <= s[index] && s[index] <= '9')
            {
                d = int(s[index] - '0');
            
                if(ans > INT_MIN / 10 || (ans == INT_MIN / 10 && d <= -(INT_MIN % 10)))
                {
                    ans = ans * 10 - d;
                }
                else
                {
                    return INT_MIN;
                }
            }
        }
        else
        {
            if(s[index] == '+')
            {
                ++index;
            }

            while(index < size && '0' <= s[index] && s[index] <= '9')
            {
                d = int(s[index] - '0');
            
                if(ans < INT_MAX / 10 || (ans == INT_MAX / 10 && d <= INT_MAX % 10))
                {
                    ans = ans * 10 + d;   
                    ++index; 
                }
                else
                {
                    return INT_MAX;
                }
            }
        }

        return ans;       
    }
};