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g0001_0100.s0065_valid_number.readme.md Maven / Gradle / Ivy

65\. Valid Number

Hard

A **valid number** can be split up into these components (in order):

1.  A **decimal number** or an **integer**.
2.  (Optional) An `'e'` or `'E'`, followed by an **integer**.

A **decimal number** can be split up into these components (in order):

1.  (Optional) A sign character (either `'+'` or `'-'`).
2.  One of the following formats:
    1.  One or more digits, followed by a dot `'.'`.
    2.  One or more digits, followed by a dot `'.'`, followed by one or more digits.
    3.  A dot `'.'`, followed by one or more digits.

An **integer** can be split up into these components (in order):

1.  (Optional) A sign character (either `'+'` or `'-'`).
2.  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 `s`, return `true` _if_ `s` _is a **valid number**_.

**Example 1:**

**Input:** s = "0"

**Output:** true 

**Example 2:**

**Input:** s = "e"

**Output:** false 

**Example 3:**

**Input:** s = "."

**Output:** false 

**Example 4:**

**Input:** s = ".1"

**Output:** true 

**Constraints:**

*   `1 <= s.length <= 20`
*   `s` consists of only English letters (both uppercase and lowercase), digits (`0-9`), plus `'+'`, minus `'-'`, or dot `'.'`.