lcm

1/**
2 * Calculates the least common multiple (LCM) of two integers.
3 *
4 * @param a - First integer
5 * @param b - Second integer
6 * @returns The least common multiple of a and b, or 0 if either input is 0
7 * @throws If inputs are not finite integers
8 */
9export function lcm(a: number, b: number): number {
10  if (!Number.isInteger(a) || !Number.isInteger(b)) {
11    throw new Error('Inputs must be integers');
12  }
13
14  if (a === 0 || b === 0) return 0;
15
16  return Math.abs(a * b) / gcd(a, b);
17}

1test('lcm - basic case', () => {
2  expect(lcm(4, 6)).toBe(12);
3});
4
5test('lcm - one is multiple of the other', () => {
6  expect(lcm(5, 20)).toBe(20);
7});
8
9test('lcm - same numbers', () => {
10  expect(lcm(7, 7)).toBe(7);
11});
12
13test('lcm - one is zero', () => {
14  expect(lcm(0, 10)).toBe(0);
15  expect(lcm(10, 0)).toBe(0);
16});
17
18test('lcm - negative inputs', () => {
19  expect(lcm(-3, 5)).toBe(15);
20  expect(lcm(3, -5)).toBe(15);
21  expect(lcm(-3, -5)).toBe(15);
22});
23
24test('lcm - throws on non-integer', () => {
25  expect(() => lcm(2.5, 3)).toThrow('Inputs must be integers');
26  expect(() => lcm(3, NaN)).toThrow('Inputs must be integers');
27});