Problem
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.