Ala Ayyad CS7

src/linked-list.js

@@ -9,17 +9,57 @@ class LinkedList {
   // If the list is empty, the new element is considered the tail as well as the head
   // If there is one element in the list before the new element is added, the new element becomes the tail of the list
   addToTail(value) {
-
+    const newNode = {
+      next: null,
+      value,
+    };
+    // check if a head already exists
+    if (this.head === null) {
+      // our list is empty
+      this.head = newNode;
+      this.tail = newNode;
+    } else {
+      // list is not empty
+      this.tail.next = newNode;
+      this.tail = newNode;
+    }
   }
   // Removes the current head node from the list, replacing it with the next element in the list
   // Returns the value of the removed node
   removeHead() {
-
+    // there may be nothing in our list
+    if (this.head === null) return;
+    // there may be one node in our list
+    if (this.head.next === null) {
+      // create a new reference to our current head, so that we can return the value
+      const head = this.head;
+      // set this.head to null
+      this.head = null;
+      // set this.tail to null
+      this.tail = null;
+      // return the value from our head
+      return head.value;
+    }
+    // there may be multiple nodes in our list
+    const head = this.head;
+    this.head = this.head.next;
+    return head.value;
   }
   // Checks the linked list for the given value
   // Returns true if the the value is found in the list, false otherwise
   contains(value) {
-
+    // if the linked list is emtpy, then automatically return false
+    if (this.head === null) return false;
+    const searchLinkedList = (node) => {
+      // base case 1: if the current node we're looking at has the value we're looking for
+      if (node.value === value) return true;
+      // base case 2: we've reached the end of our linked list
+      if (node.next === null) return false;
+      // call our function recursively, passing it the next node in our linked list
+      return searchLinkedList(node.next);
+    };
+    // call our recursive function on our first linked list node
+    return searchLinkedList(this.head);
   }
 }
 

src/queue.js

@@ -1,11 +1,64 @@
+/* eslint-disable */
 /*
   1. Add a constructor with a storage structure; there are multiple options you could use for this
   2. Add a size getter that returns the number of items the queue is storing
   3. Add an `enqueue` method that accepts an item as input and adds it to the storage structure
   4. Add a `dequeue` method that removes the item in the queue that was added earliest
 */
 class Queue {
+  constructor() {
+    this.length = 0;
 
-}
+    this.head = null;
+    this.tail = null;
+  }
+  enqueue(value) {
+    this.length++;
+    const newItem = {
+      value,
+      next: null,
+    };
+
+    if (!this.head) {
+      this.head = newItem;
+      this.tail = newItem;
+    } else {
+      this.tail.next = newItem;
+      this.tail = newItem;
+    }
+  }
+  dequeue() {
+    if (this.length === 0) return 0;
+
+    this.length--;
 
-module.exports = Queue;
+    if (!this.head) return null;
+    if (!this.head.next) this.tail = null;
+
+    const returnVal = this.head.value;
+    this.head = this.head.next;
+    return returnVal;
+  }
+  get size() {
+    return this.length;
+  }
+}
+// class Queue {
+//   constructor() {
+//     this.queue = [];
+//     this.size = 0;
+//   }
+//   enqueue(item) {
+//     this.queue.push(item);
+//     this.size++;
+//   }
+//   dequeue(item) {
+//     if (this.queue.length === 0) return 'empty';
+//     this.size--;
+//     return this.queue.shift();
+//   }
+//   size() {
+//     if (this.size < 0) return 0;
+//     return this.size;
+//   }
+// }

src/stack.js

@@ -5,7 +5,40 @@
   4. Add a `pop` method that removes the most recently-added item to the stack
 */
 class Stack {
+  constructor() {
+    this.length = 0;
 
+    this.head = null;
+    this.tail = null;
+  }
+  push(value) {
+    this.length++;
+    const newItem = {
+      value,
+      next: null,
+    };
+
+    if (this.head) {
+      this.head = newItem;
+      this.tail = newItem;
+    }
+  }
+  pop() {
+    if (this.length === 0) return 0;
+
+    this.length--;
+
+    if (!this.head) return null;
+    if (!this.head.next) this.tail = null;
+
+    const returnVal = this.head.value;
+    this.head = this.head.next;
+    return returnVal;
+  }
+  get size() {
+    return this.length;
+  }
 }
 
+
 module.exports = Stack;