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Commit 7be5ce0

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chore: Merge pull request #748 from chiranjeev-thapliyal/master
added Backtracking/AllCombinationsOfSizeK
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‎Backtracking/AllCombinationsOfSizeK.js

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/*
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Problem: Given two numbers, n and k, make all unique combinations of k numbers from 1 to n and in sorted order
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What is combinations?
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- Combinations is selecting items froms a collections without considering order of selection
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Example:
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- We have an apple, a banana, and a jackfruit
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- We have three objects, and need to choose two items, then combinations will be
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1. Apple & Banana
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2. Apple & Jackfruit
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3. Banana & Jackfruit
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To read more about combinations, you can visit the following link:
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- https://betterexplained.com/articles/easy-permutations-and-combinations/
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Solution:
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- We will be using backtracking to solve this questions
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- Take one element, and make all them combinations for k-1 elements
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- Once we get all combinations of that element, pop it and do same for next element
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*/
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class Combinations {
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constructor (n, k) {
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this.n = n
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this.k = k
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this.combinationArray = [] // will be used for storing current combination
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}
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findCombinations (high = this.n, total = this.k, low = 1) {
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if (total === 0) {
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console.log(this.combinationArray)
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return
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}
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for (let i = low; i <= high; i++) {
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this.combinationArray.push(i)
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this.findCombinations(high, total - 1, i + 1)
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this.combinationArray.pop()
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}
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}
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}
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export { Combinations }
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import { Combinations } from '../AllCombinationsOfSizeK'
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describe('AllCombinationsOfSizeK', () => {
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it('should return 3x2 matrix solution for n = 3 and k = 2', () => {
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const test1 = new Combinations(3, 2)
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expect(test1.findCombinations).toEqual([[1, 2], [1, 3], [2, 3]])
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})
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it('should return 6x2 matrix solution for n = 3 and k = 2', () => {
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const test2 = new Combinations(4, 2)
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expect(test2.findCombinations).toEqual([[1, 2], [1, 3], [1, 4], [2, 3], [2, 4], [3, 4]])
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})
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})

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