Leetcode: Sword finger offer 67 Convert string to integer [simulation + segmentation + discussion]

analysis

A discussion about illegality
A discussion of the first positive and negative
A discussion of significant numbers
A discussion about converting to results
Discussion on Cross-border

Ac code

class Solution:
    def strToInt(self, str: str) -> int:
        MIN = - 2 ** 31
        MAX = 2 ** 31 - 1

        str = str.strip()
        if len(str) == 0 or (str[0].isdigit() is False and str[0] not in ('+', '-')):
            return 0
        
        mul = 1
        if str[0] == '+':
            str = str[1:]
        elif str[0] == '-':
            mul = -1
            str = str[1:]
        
        digit = ''
        i = 0
        n = len(str)
        while i < n:
            if str[i].isdigit():
                digit += str[i]
                i += 1
            else:
                break
        
        if digit == '':
            return 0
        
        digit = int(digit)
        digit *= mul

        if digit < MIN:
            return MIN
        elif digit > MAX:
            return MAX
        else:
            return digit

summary

Classification routines and simulation