Shelly

lab-shelly/list-node.js

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+'use strict';
+
+module.exports = function(value) {
+  this.val = value;
+  this.next = null;
+};

lab-shelly/package.json

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+{
+  "name": "lab-shelly",
+  "version": "1.0.0",
+  "description": "data structure",
+  "main": "list-node.js",
+  "directories": {
+    "test": "test"
+  },
+  "scripts": {
+    "test": "mocha"
+  },
+  "keywords": [
+    "data",
+    "structures",
+    "lab"
+  ],
+  "author": "shelly",
+  "license": "MIT",
+  "devDependencies": {
+    "chai": "^3.5.0",
+    "mocha": "^3.3.0"
+  }
+}

lab-shelly/sll.js

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+'use strict';
+
+const Node = require('./list-node');
+// [val, next]
+
+// (HEAD)[val, next] The list is empty, so we just point the head at the new node
+
+// (HEAD)[val, next] => [val, next] => [val, next] => [val, next] => [val, next]
+// Prepend() adds a new node at the HEAD       Append() adds a new node after last node
+
+//O(n)
+const SLL = module.exports = function() {
+  this.head = null;
+};
+
+SLL.prototype.prepend = function(value) {
+  let node = new Node(value);
+  if(!this.head) {
+    this.head = node;
+    return this;
+  }
+  node.next = this.head;
+  this.head = node;
+  return this;
+};
+
+//O(n)
+SLL.prototype.append = function(value) {
+  let node = new Node(value);
+  let lastNode = null;
+
+  if(!this.head) {
+    this.head = node;
+    return this;
+  }
+
+  _setLastNode(this.head);
+  lastNode.next = node;
+  return this;
+
+  function _setLastNode(node) {
+    if(!node) return;
+    lastNode = node;
+    _setLastNode(node.next);
+  }
+};
+
+//O(n)
+
+SLL.prototype.remove = function(value) {
+
+  if(this.head == null) return;
+//if head is what needs to be deleted, then reassign the head position. make head be equal to the node with value head.next
+  if(this.head == value) {
+    this.head = this.head.next;
+    return;
+  }
+
+  let current = this.head;
+
+  while(current.next != null) {
+    if (current.next.value === value) {
+      current.next = current.next.next;
+      return;
+    }
+    current = current.next; //otherwise, continue to iterate until if is met
+  }
+  //iterate thru the link list and delete one before the element we want to delete. set current nodes next pointer to equal the to-be-deleted values next pointer - so...you're skipping over the deleted one and popping it out.
+};
+
+// O(n)
+SLL.prototype.reverse = function() {
+  let current = this.head;
+  let next = null;
+  let previous = null;
+
+  while(current != null) {
+    next = current.next;
+    current.next = previous;
+    previous = current;
+    current = next;
+  }
+  this.head = previous;
+};

lab-shelly/test/sll-test.js

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+'use strict';
+
+const SLL = require('./sll');
+
+// let sll = new SLL();
+
+// console.log(sll); //head: null;
+// sll.prepend(100);
+// console.log(sll); // head { value: 100 next: null }
+// console.log(sll.prepend(200));