Merge pull request #3 from ms10398/master

Added Singly LinkedList Implementation

Data Structures/Linked List/singlylinklist.js

@@ -0,0 +1,203 @@
+/* SinglyLinkedList!!
+* A linked list is implar to an array, it hold values.
+* However, links in a linked list do not have indexes. With
+* a linked list you do not need to predetermine it's size as
+* it grows and shrinks as it is edited. This is an example of
+* a singly linked list.
+*/
+
+//Functions - add, remove, indexOf, elementAt, addAt, removeAt, view
+
+//Creates a LinkedList
+function LinkedList(){
+  //Length of linklist and head is null at start
+  var length = 0;
+  var head = null;
+
+  //Creating Node with element's value
+  var Node = function(element){
+    this.element = element;
+    this.next = null;
+  };
+
+  //Returns length
+  this.size = function(){
+    return length;
+  };
+
+  //Returns the head
+  this.head = function(){
+    return head;
+  };
+
+  //Creates a node and adds it to linklist
+  this.add = function(element){
+    var node = new Node(element);
+    //Check if its the first element
+    if(head === null){
+      head = node;
+    }
+    else {
+      var currentNode = head;
+
+      //Loop till there is node present in the list
+      while(currentNode.next){
+          currentNode = currentNode.next;
+      }
+
+      //Adding node to the end of the list
+      currentNode.next = node;
+    }
+    //Increment the length
+    length++;
+  };
+
+  //Removes the node with the value as param
+  this.remove = function(element){
+    var currentNode = head;
+    var previousNode;
+
+    //Check if the head node is the element to remove
+    if(currentNode.element === element){
+      head = currentNode.next;
+    }
+    else {
+
+      //Check which node is the node to remove
+      while(currentNode.element !== element) {
+        previousNode = currentNode;
+        currentNode = currentNode.next;
+      }
+
+      //Removing the currentNode
+      previousNode.next = currentNode.next;
+    }
+
+    //Decrementing the length
+    length--;
+  };
+
+  //Return if the list is empty
+  this.isEmpty = function(){
+    return length === 0;
+  };
+
+  //Returns the index of the element passed as param otherwise -1
+  this.indexOf = function(element) {
+    var currentNode = head;
+    var index = -1;
+
+    while(currentNode){
+      index++;
+
+      //Checking if the node is the element we are searching for
+      if(currentNode.element === element){
+        return index+1;
+      }
+      currentNode = currentNode.next;
+    }
+
+    return -1;
+  };
+
+  //Returns the element at an index
+  this.elementAt = function(index){
+    var currentNode = head;
+    var count = 0;
+    while(count < index){
+      count++;
+      currentNode = currentNode.next;
+    }
+    return currentNode.element;
+  };
+
+  //Adds the element at specified index
+  this.addAt = function(index, element){
+    index--;
+    var node = new Node(element);
+
+    var currentNode = head;
+    var previousNode;
+    var currentIndex = 0;
+
+    //Check if index is out of bounds of list
+    if(index > length){
+      return false;
+    }
+
+    //Check if index is the start of list
+    if(index === 0){
+      node.next = currentNode;
+      head = node;
+    }
+    else {
+      while (currentIndex < index) {
+        currentIndex++;
+        previousNode = currentNode;
+        currentNode = currentNode.next;
+      }
+
+      //Adding the node at specified index
+      node.next = currentNode;
+      previousNode.next = node;
+    }
+
+    //Incrementing the length
+    length++;
+  };
+
+  //Removes the node at specified index
+  this.removeAt = function(index) {
+    index--;
+    var currentNode = head;
+    var previousNode;
+    var currentIndex = 0;
+
+    //Check if index is present in list
+    if(index < 0 || index >= length){
+      return null;
+    }
+
+    //Check if element is the first element
+    if (index === 0) {
+      head = currentNode.next;
+    }
+    else {
+      while (currentIndex < index) {
+        currentIndex++;
+        previousNode = currentNode;
+        currentNode = currentNode.next;
+      }
+      previousNode.next = currentNode.next;
+    }
+
+    //Decrementing the length
+    length--;
+    return currentNode.element;
+  };
+
+  //Function to view the LinkedList
+  this.view = function () {
+    var currentNode = head;
+    var count = 0;
+    while(count < length){
+      count++;
+      console.log(currentNode.element);
+      currentNode = currentNode.next;
+    }
+  };
+};
+
+//Implementation of LinkedList
+var linklist = new LinkedList();
+linklist.add(2);
+linklist.add(5);
+linklist.add(8);
+linklist.add(12);
+linklist.add(17);
+console.log(linklist.size());
+console.log(linklist.removeAt(4));
+linklist.addAt(4,15);
+console.log(linklist.indexOf(8));
+console.log(linklist.size());
+linklist.view();