LeetCode: 字符串转换到整数

Posted 2022-12-06 chenxp2311

这是 LeetCode 上的一道题：将字符串转换到整数。

题目提示如下：

The function first discards as many whitespace characters as necessary until the first non-whitespace character is found. Then, starting from this character, takes an optional initial plus or minus sign followed by as many numerical digits as possible, and interprets them as a numerical value.

The string can contain additional characters after those that form the integral number, which are ignored and have no effect on the behavior of this function.

If the first sequence of non-whitespace characters in str is not a valid integral number, or if no such sequence exists because either str is empty or it contains only whitespace characters, no conversion is performed.

If no valid conversion could be performed, a zero value is returned. If the correct value is out of the range of representable values, INT_MAX (2147483647) or INT_MIN (-2147483648) is returned.

Python 代码：

import re

class Solution(object):
    def myAtoi(self, str):
        """
        :type str: str
        :rtype: int
        """
        r = re.match("[+-]?[0-9]+", str.strip())
        if not r:
            return 0
        y = int(r.group())
        if y < -2147483648:
            y = -2147483648
        if y > 2147483647:
            y = 2147483647
        return y

这段代码用到了 python 的正则表达式模块：import re。

提交之后，这段 python 代码的细节信息如下：

Python 代码虽然简单易懂，但是所需要的时间是 C、C++ 的 10 倍。