题目
A valid number can be split up into these components (in order):
- A decimal number or an integer.
-
(Optional) An ‘e’ or ‘E’, followed by an integer. A decimal number can be split up into these components (in order):
- (Optional) A sign character (either ‘+’ or ‘-‘).
- One of the following formats:
- At least one digit, followed by a dot ‘.’.
- At least one digit, followed by a dot ‘.’, followed by at least one digit.
-
A dot ‘.’, followed by at least one digit. An integer can be split up into these components (in order):
- (Optional) A sign character (either ‘+’ or ‘-‘).
- At least one digit. For example, all the following are valid numbers: [“2”, “0089”, “-0.1”, “+3.14”, “4.”, “-.9”, “2e10”, “-90E3”, “3e+7”, “+6e-1”, “53.5e93”, “-123.456e789”], while the following are not valid numbers: [“abc”, “1a”, “1e”, “e3”, “99e2.5”, “–6”, “-+3”, “95a54e53”].
Given a string s, return true if s is a valid number.
解题思路
使用正则表达式匹配
代码
class Solution:
def isNumber(self, s: str) -> bool:
pattern = re.compile(r'^[+-]?(\d+|\d+\.\d*|\.\d+)([eE][+-]?\d+)?$')
return pattern.match(s) is not None
