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1 change: 1 addition & 0 deletions DIRECTORY.md
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Expand Up @@ -29,6 +29,7 @@
* [Is Even](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/maths/is_even.ts)
* [Is Leap Year](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/maths/is_leap_year.ts)
* [Is Odd](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/maths/is_odd.ts)
* [Is Palindrome](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/maths/is_palindrome.ts)
* [Is Square Free](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/maths/is_square_free.ts)
* [Lowest Common Multiple](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/maths/lowest_common_multiple.ts)
* [Perfect Square](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/maths/perfect_square.ts)
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21 changes: 21 additions & 0 deletions maths/is_palindrome.ts
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/**
* A function to see if a number is a palindrome.
* Note that if the reversed number is larger than MAX_SAFE_INTEGER, rounding errors may occur and the result may be incorrect.
* Time Complexity: O(log(n))
*
* @param number The input number.
* @return {boolean} Wether the number is a Palindrome or not.
*/
export const IsPalindrome = (number: number): boolean => {
if (number < 0 || (number % 10 === 0 && number !== 0)) {
return false;
}

let reversed: number = 0;
while (number > reversed) {
reversed = reversed * 10 + (number % 10);
number = Math.floor(number / 10);
}

return number === reversed || number === Math.floor(reversed / 10);
};
10 changes: 10 additions & 0 deletions maths/test/is_palindrome.test.ts
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import { IsPalindrome } from "../is_palindrome";

describe("IsPalindrome", () => {
test.each([[5, true], [1234, false], [12321, true], [31343, false]])(
"correct output for %i",
(nums, expected) => {
expect(IsPalindrome(nums)).toBe(expected);
},
);
});