freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/data-structures/perform-a-union-on-two-sets.english.md

id, title, challengeType, isHidden, forumTopicId

id	title	challengeType	isHidden	forumTopicId
587d8253367417b2b2512c6c	Perform a Union on Two Sets	1	false	301708

Description

In this exercise we are going to perform a union on two sets of data. We will create a method on our Set data structure called union. This method should take another Set as an argument and return the union of the two sets, excluding any duplicate values. For example, if setA = ['a','b','c'] and setB = ['a','b','d','e'], then the union of setA and setB is: setA.union(setB) = ['a', 'b', 'c', 'd', 'e'].

Instructions

Tests

tests:
  - text: Your <code>Set</code> class should have a <code>union</code> method.
    testString: assert((function(){var test = new Set(); return (typeof test.union === 'function')})());
  - text: The union of <code>["a", "b", "c"]</code> and <code>["c", "d"]</code> should return <code>["a", "b", "c", "d"]</code>.
    testString: assert((function(){var setA = new Set();  var setB = new Set();  setA.add('a');  setA.add('b');  setA.add('c');  setB.add('c');  setB.add('d');  var unionSetAB = setA.union(setB); var final = unionSetAB.values(); return (final.indexOf('a') !== -1 && final.indexOf('b') !== -1 && final.indexOf('c') !== -1 && final.indexOf('d') !== -1 && final.length === 4)})());

Challenge Seed

class Set {
  constructor() {
    // This will hold the set
    this.dictionary = {};
    this.length = 0;
  }
  // this method will check for the presence of an element and return true or false
  has(element) {
    return this.dictionary[element] !== undefined;
  }
  // this method will return all the values in the set
  values() {
    return Object.keys(this.dictionary);
  }
  // this method will add an element to the set
  add(element) {
    if (!this.has(element)) {
      this.dictionary[element] = true;
      this.length++;
      return true;
    }

    return false;
  }
  // this method will remove an element from a set
  remove(element) {
    if (this.has(element)) {
      delete this.dictionary[element];
      this.length--;
      return true;
    }

    return false;
  }
  // this method will return the size of the set
  size() {
    return this.length;
  }
  // change code below this line

  // change code above this line
}

Solution

class Set {
  constructor() {
    this.dictionary = {};
    this.length = 0;
  }

  has(element) {
    return this.dictionary[element] !== undefined;
  }

  values() {
    return Object.keys(this.dictionary);
  }

  add(element) {
    if (!this.has(element)) {
      this.dictionary[element] = true;
      this.length++;
      return true;
    }

    return false;
  }

  remove(element) {
    if (this.has(element)) {
      delete this.dictionary[element];
      this.length--;
      return true;
    }

    return false;
  }

  size() {
    return this.length;
  }

  union(set) {
    const newSet = new Set();
    this.values().forEach(value => {
      newSet.add(value);
    })
    set.values().forEach(value => {
      newSet.add(value);
    })

    return newSet;
  }
}