Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly
Sign up
Appearance settings

Add LuhnAlgorithm.js and LuhnAlgorithm.test.js in Maths folder #1768

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
ghost wants to merge 5 commits into TheAlgorithms:master from unknown repository
Closed
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
114 changes: 114 additions & 0 deletions Maths/LuhnAlgorithm.js
View file Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,114 @@
/**
* Luhn algorithm, also known as the "Modulus 10" or "mod 10" algorithm.
* This algorithm is a simple checksum formula used to validate the authenticity of credit card numbers.
* The Luhn algorithm works by doubling every second digit from right to left, adding the resulting digits, and then checking if the total is divisible by 10.
* If it is, the credit card number is considered valid.
* The Luhn algorithm is widely used in credit card verification and is specified in ISO/IEC 7812-1.
* It is not intended to be a cryptographically secure hash function but rather a simple method to detect accidental errors, not malicious attacks.
* https://en.wikipedia.org/wiki/Luhn_algorithm
*/

// Valid credit card numbers
export const valid1 = [4, 5, 3, 9, 6, 7, 7, 9, 0, 8, 0, 1, 6, 8, 0, 8]
export const valid2 = [5, 5, 3, 5, 7, 6, 6, 7, 6, 8, 7, 5, 1, 4, 3, 9]
export const valid3 = [6, 0, 1, 1, 1, 4, 4, 3, 4, 0, 6, 8, 2, 9, 0, 5]
export const valid4 = [3, 7, 1, 6, 1, 2, 0, 1, 9, 9, 8, 5, 2, 3, 6]
export const valid5 = [4, 5, 3, 9, 4, 0, 4, 9, 6, 7, 8, 6, 9, 6, 6, 6]

// Invalid credit card numbers
export const invalid1 = [4, 5, 3, 2, 7, 7, 8, 7, 7, 1, 0, 9, 1, 7, 9, 5]
export const invalid2 = [5, 7, 9, 5, 5, 9, 3, 3, 9, 2, 1, 3, 4, 6, 4, 3]
export const invalid3 = [3, 7, 5, 7, 9, 6, 0, 8, 4, 4, 5, 9, 9, 1, 4]
export const invalid4 = [6, 0, 1, 1, 1, 2, 7, 9, 6, 1, 7, 7, 7, 9, 3, 5]
export const invalid5 = [5, 3, 8, 2, 0, 1, 9, 7, 7, 2, 8, 8, 3, 8, 5, 4]

// Mixed batch of credit card numbers
export const mystery1 = [3, 4, 4, 8, 0, 1, 9, 6, 8, 3, 0, 5, 4, 1, 4]
export const mystery2 = [5, 4, 6, 6, 1, 0, 0, 8, 6, 1, 6, 2, 0, 2, 3, 9]
export const mystery3 = [
6, 0, 1, 1, 3, 7, 7, 0, 2, 0, 9, 6, 2, 6, 5, 6, 2, 0, 3
]
export const mystery4 = [4, 9, 2, 9, 8, 7, 7, 1, 6, 9, 2, 1, 7, 0, 9, 3]
export const mystery5 = [4, 9, 1, 3, 5, 4, 0, 4, 6, 3, 0, 7, 2, 5, 2, 3]

export const batch = [
valid1,
valid2,
valid3,
valid4,
valid5,
invalid1,
invalid2,
invalid3,
invalid4,
invalid5,
mystery1,
mystery2,
mystery3,
mystery4,
mystery5
]

/**
* Validates a credit card number using the Luhn Algorithm.
* @param {number[]} numArr - Array representing the credit card number.
* @returns {boolean} - True if the card is valid, false otherwise.
*/
export function validateCred(numArr) {
let total = 0
for (let i = numArr.length - 1; i >= 0; i--) {
let currValue = numArr[i]
// Double every other digit starting from the second-to-last
if ((numArr.length - 1 - i) % 2 === 1) {
currValue *= 2
if (currValue > 9) {
currValue -= 9
}
}
total += currValue
}
return total % 10 === 0
}

/**
* Finds invalid credit card numbers from a batch.
* @param {number[][]} cards - Array of credit card numbers.
* @returns {number[][]} - Array of invalid credit card numbers.
*/
export function findInvalidCards(cards) {
return cards.filter((card) => !validateCred(card))
}

/**
* Identifies credit card companies that issued invalid card numbers.
* @param {number[][]} invalidBatch - Array of invalid credit card numbers.
* @returns {string[]} - Array of company names.
*/
export function idInvalidCardCompanies(invalidBatch) {
const companies = new Set()
invalidBatch.forEach((card) => {
switch (card[0]) {
case 3:
companies.add('Amex')
break
case 4:
companies.add('Visa')
break
case 5:
companies.add('Mastercard')
break
case 6:
companies.add('Discover')
break
default:
console.warn('Company not found for card starting with:', card[0])
}
})
return Array.from(companies)
}

// Example Usage
console.log(validateCred(valid1)) // Should print true
console.log(validateCred(invalid1)) // Should print false
console.log(findInvalidCards(batch)) // Find all invalid cards
console.log(idInvalidCardCompanies(findInvalidCards(batch))) // Find companies of invalid cards
80 changes: 80 additions & 0 deletions Maths/test/LuhnAlgorithm.test.js
View file Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,80 @@
// Import the functions to be tested
import {
validateCred,
findInvalidCards,
idInvalidCardCompanies
} from '../LuhnAlgorithm.js'
// Import credit card numbers to be tested
import {
valid1,
valid2,
valid3,
valid4,
valid5,
invalid1,
invalid2,
invalid3,
invalid4,
invalid5,
batch
} from '../LuhnAlgorithm.js'

describe('Luhn Algorithm Tests', () => {
// Test for validateCred function
describe('validateCred', () => {
test('should return true for valid credit cards', () => {
const validCards = [valid1, valid2, valid3, valid4, valid5]
validCards.forEach((card) => {
expect(validateCred(card)).toBe(true)
})
})

test('should return false for invalid credit cards', () => {
const invalidCards = [invalid1, invalid2, invalid3, invalid4, invalid5]
invalidCards.forEach((card) => {
expect(validateCred(card)).toBe(false)
})
})
})

// Test for findInvalidCards function
describe('findInvalidCards', () => {
test('should return only invalid credit cards from a batch', () => {
const invalidCards = findInvalidCards(batch)
const allInvalid = invalidCards.every((card) => !validateCred(card))
expect(allInvalid).toBe(true)
})

test('should return an empty array if no invalid cards are found', () => {
const validCards = [valid1, valid2, valid3, valid4, valid5]
const invalidCards = findInvalidCards(validCards)
expect(invalidCards).toEqual([])
})
})

// Test for idInvalidCardCompanies function
describe('idInvalidCardCompanies', () => {
test('should identify all companies that issued invalid cards', () => {
const invalidCards = findInvalidCards(batch)
const companies = idInvalidCardCompanies(invalidCards)

// Expect the companies array to include known companies
expect(companies).toEqual(
expect.arrayContaining(['Visa', 'Mastercard', 'Amex', 'Discover'])
)
})

test('should return an empty array if no invalid cards are found', () => {
const validCards = [valid1, valid2, valid3, valid4, valid5]
const invalidCards = findInvalidCards(validCards) // Ensure only invalid cards are processed
const companies = idInvalidCardCompanies(invalidCards)
expect(companies).toEqual([])
})

test('should handle unknown card companies gracefully', () => {
const unknownCard = [9, 3, 1, 8, 2, 0, 7, 4, 5, 6, 7, 8, 9]
const companies = idInvalidCardCompanies([unknownCard])
expect(companies).not.toContain('Unknown')
})
})
})
Loading

AltStyle によって変換されたページ (->オリジナル) /