Add Algorithms to Math with tests (TheAlgorithms#429)

* chore: add area and area test

* chore: add armstrong number

* chore: add factors

* chore: add perfect cube

* chore: add perfect square

* chore: add perfect number

* chore: add number of digits

* chore: fix according to standardjs

* chore: remove conflicting files

Author: ephraimduncan

Diff for: Maths/ArmstrongNumber.js

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+/**
+ * Author: dephraiim
+ * License: GPL-3.0 or later
+ *
+ * An Armstrong number is equal to the sum of the cubes of its digits.
+ * For example, 370 is an Armstrong number because 3*3*3 + 7*7*7 + 0*0*0 = 370.
+ * An Armstrong number is often called Narcissistic number.
+ *
+ */
+
+const armstrongNumber = (num) => {
+  if (num < 0 || typeof num !== 'number') return false
+
+  let newSum = 0
+
+  const numArr = num.toString().split('')
+  numArr.forEach((num) => {
+    newSum += parseInt(num) ** numArr.length
+  })
+
+  return newSum === num
+}
+
+export { armstrongNumber }

Diff for: Maths/Factors.js

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+/**
+ * Author: dephraiim
+ * License: GPL-3.0 or later
+ *
+ * More on Factors:
+ *      https://www.mathsisfun.com/definitions/factor.html
+ *
+ */
+
+const factorsOfANumber = (number = 0) => {
+  return Array.from(Array(number + 1).keys()).filter(
+    (num) => number % num === 0
+  )
+}
+
+export { factorsOfANumber }

Diff for: Maths/NumberOfDigits.js

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+/**
+ *
+ * Author: dephraiim
+ * License: GPL-3.0 or later
+ *
+ * Returns the number of digits of a given integer
+ *
+ */
+
+const numberOfDigit = (n) => Math.abs(n).toString().length
+
+export { numberOfDigit }

Diff for: Maths/PerfectCube.js

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+/**
+ * Author: dephraiim
+ * License: GPL-3.0 or later
+ *
+ */
+
+const perfectCube = (num) => Math.round(num ** (1 / 3)) ** 3 === num
+
+export { perfectCube }

Diff for: Maths/PerfectNumber.js

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+/**
+ * Author: dephraiim
+ * License: GPL-3.0 or later
+ *
+ * == Perfect Number ==
+ * In number theory, a perfect number is a positive integer that is equal to the sum of
+ * its positive divisors(factors), excluding the number itself.
+ * For example: 6 ==> divisors[1, 2, 3, 6]
+ *      Excluding 6, the sum(divisors) is 1 + 2 + 3 = 6
+ *      So, 6 is a Perfect Number
+ * Other examples of Perfect Numbers: 28, 486, ...
+ *
+ * More on Perfect Number:
+ *      https://en.wikipedia.org/wiki/Perfect_number
+ *
+ */
+
+const factorsExcludingNumber = (n) => {
+  return [...Array(n).keys()].filter((num) => n % num === 0)
+}
+
+const perfectNumber = (n) => {
+  const factorSum = factorsExcludingNumber(n).reduce((num, initialValue) => {
+    return num + initialValue
+  }, 0)
+
+  return factorSum === n
+}
+
+export { perfectNumber }

Diff for: Maths/PerfectSquare.js

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+/**
+ * Author: dephraiim
+ * License: GPL-3.0 or later
+ *
+ */
+
+const perfectSquare = (num) => Math.sqrt(num) ** 2 === num
+
+export { perfectSquare }

Diff for: Maths/test/ArmstrongNumber.test.js

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+import { armstrongNumber } from '../ArmstrongNumber'
+
+describe('ArmstrongNumber', () => {
+  it('should return true for an armstrong number', () => {
+    expect(armstrongNumber(371)).toBeTruthy()
+  })
+
+  it('should return false for a non-armstrong number', () => {
+    expect(armstrongNumber(300)).toBeFalsy()
+  })
+  it('should return false for negative values', () => {
+    expect(armstrongNumber(-2)).toBeFalsy()
+  })
+})

Diff for: Maths/test/Factors.test.js

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+import { factorsOfANumber } from '../Factors'
+
+describe('Factors', () => {
+  factorsOfANumber(50).forEach((num) => {
+    it(`${num} is a factor of 50`, () => {
+      const isFactor = 50 % num === 0
+      expect(isFactor).toBeTruthy()
+    })
+  })
+})

Diff for: Maths/test/NumberOfDigits.test.js

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+import { numberOfDigit } from '../NumberOfDigits'
+
+describe('NumberOfDigits', () => {
+  it('should return the correct number of digits for an integer', () => {
+    expect(numberOfDigit(1234000)).toBe(7)
+  })
+
+  it('should return the correct number of digits for a negative number', () => {
+    expect(numberOfDigit(-2346243)).toBe(7)
+  })
+})

Diff for: Maths/test/PerfectCube.test.js

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+import { perfectCube } from '../PerfectCube'
+
+describe('PerfectCube', () => {
+  it('should return true for a perfect cube', () => {
+    expect(perfectCube(125)).toBeTruthy()
+  })
+  it('should return false for a non perfect cube', () => {
+    expect(perfectCube(100)).toBeFalsy()
+  })
+})

Diff for: Maths/test/PerfectNumber.test.js

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+import { perfectNumber } from '../PerfectNumber'
+
+describe('PerfectNumber', () => {
+  it('should return true for a perfect cube', () => {
+    expect(perfectNumber(28)).toBeTruthy()
+  })
+  it('should return false for a non perfect cube', () => {
+    expect(perfectNumber(10)).toBeFalsy()
+  })
+})

Diff for: Maths/test/PerfectSquare.test.js

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+import { perfectSquare } from '../PerfectSquare'
+
+describe('PerfectSquare', () => {
+  it('should return true for a perfect cube', () => {
+    expect(perfectSquare(16)).toBeTruthy()
+  })
+  it('should return false for a non perfect cube', () => {
+    expect(perfectSquare(10)).toBeFalsy()
+  })
+})