Added gcd function

Author: IPRIT

src/lib/math/index.ts

@@ -2,3 +2,4 @@ export * from './is-power-of-two/is-power-of-two';
 export * from './nearest-highest-power-of-two/nearest-highest-power-of-two';
 export * from './nearest-highest-power-of-two-result/nearest-highest-power-of-two-result';
 export * from './greatest-common-divisor/greatest-common-divisor';
+export * from './least-common-multiple/least-common-multiple';

src/lib/math/least-common-multiple/least-common-multiple.spec.ts

@@ -0,0 +1,39 @@
+// tslint:disable:no-expression-statement
+import test from 'ava';
+import { leastCommonMultiple } from './least-common-multiple';
+
+test('finds LCM of positive numbers', t => {
+  const tests = [
+    [[4, 6], 12],
+    [[334, 525252], 87717084],
+    [[100000004, 244127], 1877900075116],
+    [[1000000001, 513], 27000000027]
+  ];
+  for (const vtest of tests) {
+    const [v, a] = vtest;
+    // @ts-ignore
+    t.is(leastCommonMultiple(...v), a);
+  }
+});
+
+test('finds LCM of negative numbers', t => {
+  const tests = [
+    [[-4, -6], 12],
+    [[-334, 525252], 87717084],
+    [[-100000004, 244127], 1877900075116],
+    [[1000000001, -513], 27000000027]
+  ];
+  for (const vtest of tests) {
+    const [v, a] = vtest;
+    // @ts-ignore
+    t.is(leastCommonMultiple(...v), a);
+  }
+});
+
+test('finds LCM of 1 and 1', t => {
+  t.is(leastCommonMultiple(1, 1), 1);
+});
+
+test('works LCM with zero values', t => {
+  t.is(leastCommonMultiple(0, 0), 0);
+});

src/lib/math/least-common-multiple/least-common-multiple.ts

@@ -0,0 +1,14 @@
+import { greatestCommonDivisor } from '..';
+
+/**
+ * Returns least common multiple of two numbers using GCD
+ *
+ * @link https://en.wikipedia.org/wiki/Least_common_multiple#Using_the_greatest_common_divisor
+ *
+ * @param {number} a
+ * @param {number} b
+ * @returns {number}
+ */
+export function leastCommonMultiple(a: number, b: number): number {
+  return Math.abs(a * b) / greatestCommonDivisor(a, b);
+}