解析
8. String to Integer (atoi)
def myAtoi(self, s: str) -> int:
s = s.lstrip()
sign = 1
if s:
if s[0] == "+":
s = s[1:]
elif s[0] == "-":
sign = -1
s = s[1:]
res = 0
for c in s:
if c in "0123456789":
res = res * 10 + int(c)
else:
break
res *= sign
return min(2 ** 31 - 1, max(res, -2 ** 31))