Update AllCombinationsOfSizeK.js (#1530)

* Update AllCombinationsOfSizeK.js

* Update AllCombinationsOfSizeK.js

* Update AllCombinationsOfSizeK.test.js

Changes made it the type of testing. 
Instead of testing the class now the program will test the function

* Update AllCombinationsOfSizeK.js

* Update AllCombinationsOfSizeK.js

* Update AllCombinationsOfSizeK.js

* Update AllCombinationsOfSizeK.test.js

* Update AllCombinationsOfSizeK.test.js

Author: imrahulkb

Backtracking/AllCombinationsOfSizeK.js

@@ -1,46 +1,28 @@
-/*
-  Problem: Given two numbers, n and k, make all unique combinations of k numbers from 1 to n and in sorted order
-
-  What is combinations?
-  - Combinations is selecting items from a collections without considering the order of selection
-
-  Example:
-  - We have an apple, a banana, and a jackfruit
-  - We have three objects, and need to choose two items, then combinations will be
-
-  1. Apple & Banana
-  2. Apple & Jackfruit
-  3. Banana & Jackfruit
-
-  To read more about combinations, you can visit the following link:
-  - https://betterexplained.com/articles/easy-permutations-and-combinations/
-
-  Solution:
-  - We will be using backtracking to solve this questions
-  - Take one element, and make all them combinations for k-1 elements
-  - Once we get all combinations of that element, pop it and do same for next element
-*/
-
-class Combinations {
-  constructor(n, k) {
-    this.n = n
-    this.k = k
-    this.current = [] // will be used for storing current combination
-    this.combinations = []
-  }
-
-  findCombinations(high = this.n, total = this.k, low = 1) {
-    if (total === 0) {
-      this.combinations.push([...this.current])
-      return this.combinations
+function generateCombinations(n, k) {
+  let currentCombination = []
+  let allCombinations = [] // will be used for storing all combinations
+  let currentValue = 1
+
+  function findCombinations() {
+    if (currentCombination.length === k) {
+      // Add the array of size k to the allCombinations array
+      allCombinations.push([...currentCombination])
+      return
     }
-    for (let i = low; i <= high; i++) {
-      this.current.push(i)
-      this.findCombinations(high, total - 1, i + 1)
-      this.current.pop()
+    if (currentValue > n) {
+      // Check for exceeding the range
+      return
     }
-    return this.combinations
+    currentCombination.push(currentValue++)
+    findCombinations()
+    currentCombination.pop()
+    findCombinations()
+    currentValue--
   }
+
+  findCombinations()
+
+  return allCombinations
 }
 
-export { Combinations }
+export { generateCombinations }

Backtracking/tests/AllCombinationsOfSizeK.test.js

@@ -1,18 +1,18 @@
-import { Combinations } from '../AllCombinationsOfSizeK'
+import { generateCombinations } from '../AllCombinationsOfSizeK'
 
 describe('AllCombinationsOfSizeK', () => {
   it('should return 3x2 matrix solution for n = 3 and k = 2', () => {
-    const test1 = new Combinations(3, 2)
-    expect(test1.findCombinations()).toEqual([
+    const res = generateCombinations(3, 2)
+    expect(res).toEqual([
       [1, 2],
       [1, 3],
       [2, 3]
     ])
   })
 
   it('should return 6x2 matrix solution for n = 4 and k = 2', () => {
-    const test2 = new Combinations(4, 2)
-    expect(test2.findCombinations()).toEqual([
+    const res = generateCombinations(4, 2)
+    expect(res).toEqual([
       [1, 2],
       [1, 3],
       [1, 4],