LeetCode刷题：8. 字符串转换整数 (atoi)

最新推荐文章于 2025-06-03 18:15:13 发布

Coder_Penguin

最新推荐文章于 2025-06-03 18:15:13 发布

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class Solution {
public:
    int myAtoi(string s) {
        if(s.empty()) return 0;
        int i = 0;
        while(s[i] ==' ')
            ++i;
        s = s.substr(i);
        int positivenum = 0,negativenum = 0,numnum = 0;
        long long int res = 0;
        for(i = 0; i < s.size();i++)
        {
            if(s[i] == '-')
            {
                if(positivenum == 0 && negativenum == 0 && numnum == 0)
                    negativenum = 1;
                else
                    break;
            }
            else if(s[i] == '+')
            {
                if(positivenum == 0&&negativenum == 0&&numnum == 0)
                    positivenum = 1;
                else
                    break;
            }
            else if(std::isdigit(s[i]))
            {
                res = res *10 + s[i] - '0';
                if(res > INT_MAX)
                    break;
                numnum = 1;
            }
            else 
                break;
        }
        if(negativenum == 1)
            res = -1 * res;
        if(res < 0)
            res = std::max(res, (long long)INT_MIN);
        if(res > 0) 
            res = std::min(res, (long long)INT_MAX);
        return res;
    }
};