Add recursive factorial function (#85)

* Fix LinkedList

* Fix the prepend method for the LinkedList

* Fix the remove method for the MinHeap

* Correct a comment

* Fix BST removal method

* Fix the findEdge method of the graph

* Fix the value returned by DisjointSet union

* Add recursive factorial function

src/algorithms/math/factorial/__test__/factorialRecursive.test.js

@@ -0,0 +1,11 @@
+import factorialRecursive from '../factorialRecursive';
+
+describe('factorialRecursive', () => {
+  it('should calculate factorial', () => {
+    expect(factorialRecursive(0)).toBe(1);
+    expect(factorialRecursive(1)).toBe(1);
+    expect(factorialRecursive(5)).toBe(120);
+    expect(factorialRecursive(8)).toBe(40320);
+    expect(factorialRecursive(10)).toBe(3628800);
+  });
+});

src/algorithms/math/factorial/factorialRecursive.js

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+/**
+ * @param {number} number
+ * @return {number}
+ */
+export default function factorialRecursive(number) {
+  return number > 1 ? number * factorialRecursive(number - 1) : 1;
+}