Update AllCombinationsOfSizeK.js (TheAlgorithms#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],