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Commit 45f0b7c

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algorithm: check if integer is palindrome (TheAlgorithms#1177)
* feat: Add check number case * style: Fix formatting * fix: Remove number check part * feat: Create isPalindromeIntegerNumber * test: Add minus number case
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‎Maths/isPalindromeIntegerNumber.js‎

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/**
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* @function isPalindromeIntegerNumber
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* @param { Number } x
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* @returns {boolean} - input integer is palindrome or not
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*
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* time complexity : O(log_10(N))
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* space complexity : O(1)
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*/
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export function isPalindromeIntegerNumber (x) {
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if (typeof x !== 'number') {
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throw new TypeError('Input must be a integer number')
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}
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// check x is integer
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if (!Number.isInteger(x)) {
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return false
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}
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// if it has '-' it cannot be palindrome
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if (x < 0) return false
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// make x reverse
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let reversed = 0
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let num = x
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while (num > 0) {
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const lastDigit = num % 10
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reversed = reversed * 10 + lastDigit
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num = Math.floor(num / 10)
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}
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// compare origin x and reversed are same
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return x === reversed
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}
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import { isPalindromeIntegerNumber } from '../isPalindromeIntegerNumber'
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describe('isPalindromeIntegerNumber', () => {
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it('expects to return true when length of input is 1', () => {
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expect(isPalindromeIntegerNumber(6)).toEqual(true)
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})
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it('expects to return true when input is palindrome', () => {
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expect(isPalindromeIntegerNumber(121)).toEqual(true)
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expect(isPalindromeIntegerNumber(12321)).toEqual(true)
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expect(isPalindromeIntegerNumber(1221)).toEqual(true)
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})
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it('expects to return false when input is not palindrome', () => {
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expect(isPalindromeIntegerNumber(189)).toEqual(false)
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})
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it('expects to return false when input is minus', () => {
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expect(isPalindromeIntegerNumber(-121)).toEqual(false)
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expect(isPalindromeIntegerNumber(-12321)).toEqual(false)
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})
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it('expects to return false when input is not integer number', () => {
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expect(isPalindromeIntegerNumber(123.456)).toEqual(false)
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})
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it('expects to throw error when input is not a number', () => {
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expect(() => isPalindromeIntegerNumber(undefined)).toThrowError()
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expect(() => isPalindromeIntegerNumber({ key: 'val' })).toThrowError()
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expect(() => isPalindromeIntegerNumber([])).toThrowError()
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})
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})

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