Create 141-linked-list-cycle.js

Author: everthis

141-linked-list-cycle.js

@@ -0,0 +1,24 @@
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val) {
+ *     this.val = val;
+ *     this.next = null;
+ * }
+ */
+
+/**
+ * @param {ListNode} head
+ * @return {boolean}
+ */
+const hasCycle = function(head) {
+  const seen = []
+  while(head != null) {
+        if(seen.indexOf(head) !== -1) {
+          return true
+        } else {
+          seen.push(head)
+        }
+        head = head.next
+  }
+  return false
+};