Merge pull request #171 from SBALDOCK/master

linked list is circular linked list

circular-linked-list.js

@@ -0,0 +1,63 @@
+'use strict';
+/*
+ #148 - Problem Domain: check if a linked list is a circular linked list
+ using Floyd's Algorithm (tortoise and hare approach), return true if they meet, false if not
+*/
+
+function findCircular(linkedlist) {
+
+  let tortoise = linkedlist.head;
+  let hare = linkedlist.head;
+
+  if (linkedlist.head.next === null) {
+    return false;
+  }
+  while (hare.next && hare.next.next) {
+    tortoise = tortoise.next;
+    hare = hare.next.next;
+    if (tortoise === hare) {
+      return true;
+    }
+  }
+  return false;
+
+}
+
+// Establishing LinkedList and Node Classes
+class Node {
+  constructor(value, next = null) {
+    this.value = value;
+    this.next = next;
+  }
+}
+
+class LinkedList {
+  constructor() {
+    this.head = null;
+  }
+
+  insert(val) {
+    this.head = new Node(val, this.head);
+  }
+
+  append(val) {
+    let current = this.head;
+    while (current) {
+      current = curent.next;
+    }
+    current.next = new Node(val)
+  }
+
+  // method to create a circular linked list
+  makeCirc(val, existingNode) {
+    let node = new Node(val, existingNode);
+    let current = this.head;
+    while (current.next) {
+      current = current.next
+    }
+    current.next = node;
+  }
+}
+
+
+