[数学] leetcode 8 String to Integer (atoi)

Posted 2022-06-06 fish1996

problem:https://leetcode.com/problems/string-to-integer-atoi/

        这题题号挺前的，但一直没做。今天提了5次才过，终于知道这道题为什么通过率这么低了。主要就是if/else练习，尤其是完全没看题后会挂在很多地方。

class Solution 
public:
    int myAtoi(string str) 
        unsigned long long res = 0;
        bool bPositive = true;
        bool bFind = false;
        for(int i = 0;i < str.size();i++)
        
            if(str[i] == ‘ ‘) 
            
                if(bFind) return bPositive ? res : -res;
                else continue;
            
            if(!bFind && str[i] == ‘-‘)
            
                bFind = true;
                bPositive = false;
                continue;
            
            if(!bFind && str[i] == ‘+‘)
            
                bFind = true;
                bPositive = true;
                continue;
                       
            if(!isdigit(str[i])) return bPositive ? res : -res;
            bFind = true;
            unsigned long long num = str[i] - ‘0‘;
            res = 10 * res + num;
            if(res >= INT_MAX) 
            
                if(!bPositive)
                
                    if(res == INT_MAX) return -INT_MAX;
                    else return INT_MIN;
                
                return INT_MAX;
            
        
        return bPositive ? res : -res;
    
;