feat(maths): added Factors

maths/factors.ts

@@ -0,0 +1,24 @@
+/**
+ * @function Factors
+ * @description Find all the factors of a natural number.
+ * @param {number} num - A natural number.
+ * @return {number[]} - An array of all the factors of given natural number.
+ * @see https://en.wikipedia.org/wiki/Divisor
+ * @example Factors(1) = [1]
+ * @example Factors(4) = [1,2,4]
+ * @example Factors(16) = [1,3,5,15]
+ */
+
+export const Factors = (num: number): number[] => {
+  if (num <= 0 || !Number.isInteger(num)) {
+    throw new Error("only natural numbers are supported");
+  }
+
+  const res: number[] = [];
+  // iterate from 1 to num and push factors into the res array
+  for (let i: number = 0; i <= num; i++) {
+    if (num % i === 0) res.push(i);
+  }
+
+  return res;
+};

maths/test/factors.test.ts

@@ -0,0 +1,19 @@
+import { Factors } from "../factors";
+
+describe("Factors", () => {
+  test.each([-890, -5.56, -7, 0, 0.73, 4.2, NaN, -Infinity, Infinity])(
+    "should throw an error for non natural number %d",
+    (num) => {
+      expect(() => Factors(num)).toThrowError(
+        "only natural numbers are supported",
+      );
+    },
+  );
+
+  test.each([[1, [1]], [2, [1,2]], [4, [1,2,4]], [6, [1,2,3,6]], [16, [1,2,4,8,16]]])(
+    "of %i should return the correct array of its factors",
+    (num, expected) => {
+      expect(Factors(num)).toStrictEqual(expected);
+    },
+  );
+});