valid number solution

valid-number/README.md

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

valid-number/index.test.ts

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+import { isNumber } from "./index";
+
+describe("Valid Number", () => {
+  test("'2' is valid number", () => {
+    expect(isNumber("2")).toBe(true);
+  });
+  test("'0089' is valid number", () => {
+    expect(isNumber("0089")).toBe(true);
+  });
+  test("'-0.1' is valid number", () => {
+    expect(isNumber("-0.1")).toBe(true);
+  });
+  test("'+3.14' is valid number", () => {
+    expect(isNumber("+3.14")).toBe(true);
+  });
+  test("'4.' is valid number", () => {
+    expect(isNumber("4.")).toBe(true);
+  });
+  test("'-.9' is valid number", () => {
+    expect(isNumber("-.9")).toBe(true);
+  });
+  test("'2e10' is valid number", () => {
+    expect(isNumber("2e10")).toBe(true);
+  });
+  test("'-90E3' is valid number", () => {
+    expect(isNumber("-90E3")).toBe(true);
+  });
+  test("'3e+7' is valid number", () => {
+    expect(isNumber("3e+7")).toBe(true);
+  });
+  test("'+6e-1' is valid number", () => {
+    expect(isNumber("+6e-1")).toBe(true);
+  });
+  test("'53.5e93' is valid number", () => {
+    expect(isNumber("53.5e93")).toBe(true);
+  });
+  test("'-123.456e789' is valid number", () => {
+    expect(isNumber("-123.456e789")).toBe(true);
+  });
+  test("'abc' is NOT a valid number", () => {
+    expect(isNumber("abc")).toBe(false);
+  });
+  test("'1a' is NOT a valid number", () => {
+    expect(isNumber("1a")).toBe(false);
+  });
+  test("'1e' is NOT a valid number", () => {
+    expect(isNumber("1e")).toBe(false);
+  });
+  test("'e3' is NOT a valid number", () => {
+    expect(isNumber("e3")).toBe(false);
+  });
+  test("'99e2.5' is NOT a valid number", () => {
+    expect(isNumber("99e2.5")).toBe(false);
+  });
+  test("'--6' is NOT a valid number", () => {
+    expect(isNumber("--6")).toBe(false);
+  });
+  test("'-+3' is NOT a valid number", () => {
+    expect(isNumber("-+3")).toBe(false);
+  });
+  test("'95a54e53' is NOT a valid number", () => {
+    expect(isNumber("95a54e53")).toBe(false);
+  });
+});

valid-number/index.ts

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+import { Logger } from "../utils";
+
+export const isNumber = (s: string): boolean => {
+  const sign = `[+-]`;
+  const digit = `\\d`;
+  const digits = `(${digit}+)`;
+  const integer = `(${sign}?${digits})`;
+  const exponent = `([eE]${integer})`;
+  const decimal = `(${sign}?((${digits}[.])|(${digits}[.]${digits})|([.]${digits})))`;  
+
+  const validNumber = `(${integer}|${decimal})${exponent}?`;
+
+  const fullRegex = new RegExp(`^${validNumber}$`);
+
+  return fullRegex.test(s);
+};
+
+if (require.main === module) {
+  const args = process.argv;
+  const s = args[2] ?? null;
+
+  if (!s) {
+    Logger.warn(
+      "Assumed watch mode; Please provide an argument if not intended"
+    );
+    const ss = "-.5";
+    Logger.info(`[watch-mode] Input: "${ss}", Output: ${isNumber(ss)}`);
+  } else {
+    Logger.info(`Input: "${s}", Output: ${isNumber(args[1])}`);
+  }
+}