chore: merge "Added backtracking sum of subset (#702)"

* sum of subset algorithm

* set returns comment

* fix comment

* add resource url to comments

* separate test to different file and format

Backtracking/tests/SumOfSubset.test.js

@@ -0,0 +1,18 @@
+import { sumOfSubset } from '../SumOfSubset'
+
+describe('SumOfSubset', () => {
+  it('should return the subsets that add up to the given number', () => {
+    // W = [2, 5, 7, 8, 12, 16, 23, 40]
+    // K = 25
+
+    const nums = [2, 5, 7, 8, 12, 16, 23, 40]
+
+    const subsets = sumOfSubset(nums, [], 0, 0, 25)
+
+    expect(subsets).toEqual([
+      [2, 7, 16],
+      [2, 23],
+      [5, 8, 12]
+    ])
+  })
+})