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Commit 599263d

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Merge branch 'master' of github.com:knaxus/problem-solving-javascript into problems
2 parents 2f39c26 + bc95e85 commit 599263d

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13 files changed

+388
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‎README.md‎

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@@ -29,6 +29,8 @@ Collection of interview questions with Unit Tests. Problems includes Data Struct
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- [Postfix Expression Evaluation](src/_DataStructures_/Stack/postfix-expression-evaluation)
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- [Remove Consecutive Repeated Digits](src/_DataStructures_/Stack/remove-consecutive-repeated-digits)
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- [Implement 2 Stacks using Single Array](src/_DataStructures_/Stack/2-stacks-using1-array)
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- [Sort a Stack](src/_DataStructures_/Stack/sort-a-stack)
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- [Queue](src/_DataStructures_/Queue)
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/**
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* Sort a stack with the help of a temporary stack.
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* Input:[1,10,21,3,9,-11,32]
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* Output:[32,21,10,9,3,1,-11]
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* Time Complexity:O(N^2)
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*/
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const Stack = require('../index');
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function sortStack(stack) {
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const tempStack = new Stack();
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while (!stack.isEmpty()) {
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//pop the first element from stack
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let temp = stack.pop();
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//for ascending order (tempStack.peek() < temp)
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while (!tempStack.isEmpty() && tempStack.peek() > temp) {
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stack.push(tempStack.pop());
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}
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//push the first element(temp) onto tempStack if tempStack.peek()<temp
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tempStack.push(temp);
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}
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return tempStack;
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}
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/*
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const s = new Stack();
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s.push(1);
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s.push(10);
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s.push(21);
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s.push(3);
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s.push(9);
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s.push(-11);
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s.push(32);
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console.log(s.data);
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const s1 = sortStack(s);
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console.log(s1.data);
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*/
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const BST = require('.');
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describe('Data Structure : Binary Search Tree', () => {
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it('Should be class', () => {
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expect(typeof BST.prototype.constructor).toEqual('function');
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});
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describe('Binary Search Tree API', () => {
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let bst = null;
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beforeEach(() => {
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bst = new BST(5);
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});
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it('Should delete() an element from Binary Search Tree', () => {
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bst.add(4);
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bst.add(9);
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bst.add(2);
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bst.delete(bst.root, 4);
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expect(bst.traverseInorder()).toEqual([2, 5, 9]);
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bst.delete(bst.root, 2);
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expect(bst.traverseInorder()).toEqual([5, 9]);
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});
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});
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});
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const BinarySearchTree = require('./index');
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describe('Binary Search Tree', () => {
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let bst;
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let rootsLeftChild;
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let rootsRightChild;
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let rootsLeftChildsLeftChild;
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let rootsLeftChildsRightChild;
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let rootsRightChildsLeftChild;
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let rootsRightChildsRightChild;
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describe('Creates a binary search tree', () => {
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it('should create a bst with root 100', () => {
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bst = new BinarySearchTree(100);
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expect(bst.root.value).toEqual(100);
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});
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it('should add element 20 to the left of root node', () => {
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bst.add(20);
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rootsLeftChild = bst.root.leftChild;
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expect(rootsLeftChild.value).toEqual(20);
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});
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it('should add element 500 to the right of root node', () => {
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bst.add(500);
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rootsRightChild = bst.root.rightChild;
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expect(rootsRightChild.value).toEqual(500);
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});
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it('should add element 10 to the left of root"s left child', () => {
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bst.add(10);
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rootsLeftChildsLeftChild = bst.root.leftChild.leftChild;
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expect(rootsLeftChildsLeftChild.value).toEqual(10);
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});
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it('should add element 30 to the right of root"s left child', () => {
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bst.add(30);
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rootsLeftChildsRightChild = bst.root.leftChild.rightChild;
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expect(rootsLeftChildsRightChild.value).toEqual(30);
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});
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it('should add element 400 to the left of root"s right child', () => {
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bst.add(400);
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rootsRightChildsLeftChild = bst.root.rightChild.leftChild;
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expect(rootsRightChildsLeftChild.value).toEqual(400);
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});
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it('should add element 600 to the right of root"s right child', () => {
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bst.add(600);
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rootsRightChildsRightChild = bst.root.rightChild.rightChild;
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expect(rootsRightChildsRightChild.value).toEqual(600);
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});
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});
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describe('Check insertion was as expected', () => {
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it('Inorder traversal of the created bst should be [ 10, 20, 30, 100, 400, 500, 600 ]', () => {
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expect(bst.traverseInorder()).toEqual([10, 20, 30, 100, 400, 500, 600]);
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});
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it('Preorder traversal of the created bst should be [ 100, 20, 10, 30, 500, 400, 600 ]', () => {
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expect(bst.traversePreorder()).toEqual([100, 20, 10, 30, 500, 400, 600]);
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});
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it('Postorder traversal of the created bst should be [ 10, 30, 20, 400, 600, 500, 100 ]', () => {
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expect(bst.traversePostorder()).toEqual([10, 30, 20, 400, 600, 500, 100]);
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});
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});
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});
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/**
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* Lowest Common Ancestor in a Binary Search Tree.
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*
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* Given values of two values n1 and n2 in a Binary Search Tree, find the Lowest Common Ancestor (LCA). You may assume that both the values exist in the tree.
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*/
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function lca(node, n1, n2) {
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if (node == null)
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return null;
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// If both n1 and n2 are smaller than root, then LCA lies in left
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if (node.value > n1 && node.value > n2)
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return lca(node.leftChild, n1, n2);
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// If both n1 and n2 are greater than root, then LCA lies in right
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if (node.value < n1 && node.value < n2)
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return lca(node.rightChild, n1, n2);
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return node;
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}
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module.exports = {
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lca,
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};
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const { lca } = require('.');
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const BinarySearchTree = require('../index');
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// Quick JSON equivalent
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// {"left":{"left":{"data":4},"right":{"left":{"data":10},"right":{"data":14},"data":12},"data":8},"right":{"data":22},"data":20}
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describe('LCA', () => {
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let bst = new BinarySearchTree(20);
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bst.add(22);
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bst.add(8);
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bst.add(12);
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bst.add(4);
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bst.add(14);
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bst.add(10);
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it('Should return 12', () => {
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expect(lca(bst.root, 10, 14).value).toEqual(12);
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});
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it('Should return 8', () => {
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expect(lca(bst.root, 14, 8).value).toEqual(8);
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});
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it('Should return 20', () => {
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expect(lca(bst.root, 10, 22).value).toEqual(20);
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});
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});

‎src/_DataStructures_/Trees/SuffixTree/index.js‎

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/* eslint-disable max-len */
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/* eslint-disable no-restricted-syntax */
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/* eslint-disable no-plusplus */
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/*
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Implemented by watching this conceptually video: https://www.youtube.com/watch?v=VA9m_l6LpwI
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*/
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const alphabets = 'abcdefghijklmnopqrstuvwxyz';
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class Node {
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constructor(value, isEnd, index) {
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this.data = value;
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let currentNode = this.head;
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while (j < currentString.length) {
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if (!currentNode.next.has(currentString[j])) {
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currentNode.next.set(currentString[j], new Node(currentString, true, i));
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let nextString = '';
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while (j < currentString.length) {
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nextString += currentString[j];
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j++;
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}
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currentNode.next.set(nextString[0], new Node(nextString, true, i));
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break;
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} else {
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let k = 0;
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diffString += partialMatchString[k];
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k++;
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}
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partialMatchNode.data = matchString;
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if (diffString) {
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partialMatchNode.next.set(diffString[0], new Node(diffString, true, partialMatchNode.index));
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const oldMap = partialMatchNode.next;
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const newNode = new Node(diffString, partialMatchNode.isEnd, partialMatchNode.index);
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const alphabetsArray = alphabets.split('');
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for (const char of alphabetsArray) {
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if (oldMap.has(char)) {
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newNode.next.set(char, oldMap.get(char));
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}
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}
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partialMatchNode.next = new Map();
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partialMatchNode.next.set(diffString[0], newNode);
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partialMatchNode.isEnd = false;
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partialMatchNode.index = null;
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}
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}
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}
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// const s = new SuffixTree('banana');
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// const st = 'asdjkxhcjbzdmnsjakdhasdbajw';
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// const s = new SuffixTree(st);
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// s.constructSuffixTree();
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// // console.log(s.head.next);
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// console.log(s.findSubstring('nana'));
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// for (let i = 0; i < st.length; i++) {
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// const e = st.substring(i);
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// if (s.findSubstring(e) !== i) {
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// console.log(e, i, s.findSubstring(e));
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// }
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// }
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module.exports = SuffixTree;

‎src/_Problems_/factorial/index.js‎

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function factorial(num) {
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if (num === 1) return num;
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else return num * factorial(num - 1);
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}
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module.exports = {
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factorial,
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};
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const { factorial } = require('.');
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describe('Factorial', () => {
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it('Should return 24', () => {
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expect(factorial(4)).toEqual(24);
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});
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it('Should return 1', () => {
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expect(factorial(1)).toEqual(1);
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});
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it('Should return 120', () => {
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expect(factorial(5)).toEqual(120);
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});
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});
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const { jumpSearch, jumpSearchRecursive } = require('.');
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describe('Jump Search', () => {
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const array = [1, 2, 3, 4, 5, 6, 7, 8];
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describe('When element to find is at 1st position ', () => {
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it('Jump search', () => {
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expect(jumpSearch(array, 1)).toEqual(0);
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});
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});
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describe('When element to find is at last position ', () => {
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it('Jump search', () => {
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expect(jumpSearch(array, 7)).toEqual(6);
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});
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});
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describe('When element to find is at random position ', () => {
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it('Jump search', () => {
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expect(jumpSearch(array, 3)).toEqual(2);
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});
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});
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});

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