Add solution #141

Author: JoshCrozier

README.md

@@ -42,6 +42,7 @@
 119|[Pascal's Triangle II](./0119-pascals-triangle-ii.js)|Easy|
 121|[Best Time to Buy and Sell Stock](./0121-best-time-to-buy-and-sell-stock.js)|Easy|
 136|[Single Number](./0136-single-number.js)|Easy|
+141|[Linked List Cycle](./0141-linked-list-cycle.js)|Easy|
 151|[Reverse Words in a String](./0151-reverse-words-in-a-string.js)|Medium|
 152|[Maximum Product Subarray](./0152-maximum-product-subarray.js)|Medium|
 217|[Contains Duplicate](./0217-contains-duplicate.js)|Easy|

solutions/0141-linked-list-cycle.js

@@ -0,0 +1,38 @@
+/**
+ * 141. Linked List Cycle
+ * https://leetcode.com/problems/linked-list-cycle/
+ * Difficulty: Easy
+ *
+ * Given head, the head of a linked list, determine if the linked list has a cycle in it.
+ *
+ * There is a cycle in a linked list if there is some node in the list that can be reached
+ * again by continuously following the next pointer. Internally, pos is used to denote the
+ * index of the node that tail's next pointer is connected to. Note that pos is not passed
+ * as a parameter.
+ *
+ * Return true if there is a cycle in the linked list. Otherwise, return false.
+ */
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val) {
+ *     this.val = val;
+ *     this.next = null;
+ * }
+ */
+
+/**
+ * @param {ListNode} head
+ * @return {boolean}
+ */
+var hasCycle = function(head) {
+  while (head) {
+    if (head.visited) {
+      return true;
+    }
+    head.visited = 1;
+    head = head.next;
+  }
+
+  return false;
+};