// https://www.freecodecamp.org/learn/coding-interview-prep/data-structures/perform-a-difference-on-two-sets-of-data
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;
  }
  // This is our union method
  union(set) {
    const newSet = new Set();
    this.values().forEach((value) => {
      newSet.add(value);
    });
    set.values().forEach((value) => {
      newSet.add(value);
    });

    return newSet;
  }
  // This is our intersection method
  intersection(set) {
    const newSet = new Set();

    let largeSet;
    let smallSet;
    if (this.dictionary.length > set.length) {
      largeSet = this;
      smallSet = set;
    } else {
      largeSet = set;
      smallSet = this;
    }

    smallSet.values().forEach((value) => {
      if (largeSet.dictionary[value]) {
        newSet.add(value);
      }
    });

    return newSet;
  }
  // Only change code below this line

  difference(otherSet) {
    const diffSet = new Set();
    this.values().forEach((item) => {
      if (!otherSet.has(item)) {
        diffSet.add(item);
      }
    });
    return diffSet;
  }

  // Only change code above this line
}