Leetcode String to integer(Atoi)

^： Match the beginning of a string
[\+\-]： Representing one + Character or - character
?： The first character is optional
\d： A number
+： One or more of the preceding characters
\D： A non numeric character
*： The first character 0 One or more

class Solution:
    def myAtoi(self, s: str) -> int:
        return max(min(int(*re.findall('^[\+\-]?\d+', s.lstrip())), 2**31 - 1), -2**31)

import re
class Solution:
    def myAtoi(self, str: str) -> int:
        INT_MAX = 2147483647    
        INT_MIN = -2147483648
        str = str.lstrip()      # Clear the extra space on the left 
        num_re = re.compile(r'^[\+\-]?\d+')   # Set regular rules 
        num = num_re.findall(str)   # Find a match 
        num = int(*num) # Because it returns a list , Unpack and convert to integer 
        return max(min(num,INT_MAX),INT_MIN)    # Return value 

import re
class Solution:
    def myAtoi(self,str:str) -> int:
        INT_MAX = 2**31-1
        INT_MIN = -2**31
        str = str.lstrip()