题解 | ##

```class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param s string字符串 
     * @return int整型
     */
    int StrToInt(string s) {
        // write code here
        int flag = 0 ;
        int i = 0 ;
        int sum = 0 ;
        while(s[i]== ' ')
        {
            i++;
        }
        if(s[i] == '+')
        {
            i++;
            flag = 1;
        }
        else if(s[i] == '-')
        {
            flag = -1;
            i++;
        }
        else
        {
            flag = 1;
        }

         if(s[i] < '0' || s[i] > '9')
        {
            return 0;
        }
        int num = 0 ;
        int index = 0 ;
        while(s[i] >= '0' && s[i] <='9')
        {
            int j=s[i]-'0';
            sum = sum*10+j;
            if(sum < num)
            {
                index = 1;
                break;
            }
            num = sum;
            i++;
        }
        sum = sum * flag;
         if(index==1){
            if(flag== -1){
                sum=INT_MIN;
            }
            else{
                sum= INT_MAX;
            }
        }
        return sum;
        
    }
};