1. Linked List Cycle

Author: Sunjae95

linked-list-cycle/sunjae95.js

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+/**
+ * @description
+ * brainstorming:
+ * hash table
+ *
+ * n = length of head
+ * time complexity: O(n)
+ * space complexity: O(n)
+ */
+var hasCycle = function (head) {
+  const set = new Set();
+  let node = head;
+
+  while (node) {
+    if (set.has(node)) return true;
+    set.add(node);
+    node = node.next;
+  }
+
+  return false;
+};