DAY 10 OF CODE CHALLENGE

VALID NUMBER

DESCRIPTION OF QUESTION

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:
One or more digits, followed by a dot '.'.
One or more digits, followed by a dot '.', followed by one or more digits.
A dot '.', followed by one or more digits.
An integer can be split up into these components (in order):

(Optional) A sign character (either '+' or '-').
One or more digits.
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 x, return true if x is a valid number.

Example 1:

Input: x = "0"
Output: true
Example 2:

Input: x = "e"
Output: false
Example 3:

Input: x = "."
Output: false

PROCEDURE

• I made list of possible error conditions and checked for each one which include:

1. Seeing an 'e'/'E' when a number has not yet been seen or more than one exponent character ('e'/'E').

2. When there is more than one sign or sign appearing after a decimal or number have been seen.

3. When decimal appeared after an 'e'/'E' has been seen or more than one decimal.

4. Appearance of any other non-number character.

5. When the end of x is reached without active number.

• The above were achieved by setting some boolen flags for the different things being kept on track (exp, num, dec, sign).

OUTCOME