add Linked List Cycle solution

Author: HoonDongKang

linked-list-cycle/HoonDongKang.ts

@@ -0,0 +1,44 @@
+/**
+ * [Problem]: [141] Linked List Cycle
+ * (https://leetcode.com/problems/linked-list-cycle/description/)
+ */
+class ListNode {
+    val: number;
+    next: ListNode | null;
+    constructor(val?: number, next?: ListNode | null) {
+        this.val = val === undefined ? 0 : val;
+        this.next = next === undefined ? null : next;
+    }
+}
+
+function hasCycle(head: ListNode | null): boolean {
+    //시간복잡도 O(n)
+    //공간복잡도 O(n)
+    function setFunc(head: ListNode | null): boolean {
+        if (!head) return false;
+        const set = new Set<ListNode>();
+        let currentNode: ListNode = head;
+
+        while (currentNode) {
+            if (set.has(currentNode)) return true;
+
+            set.add(currentNode);
+            currentNode = currentNode.next!;
+        }
+
+        return false;
+    }
+    //시간복잡도 O(n)
+    //공간복잡도 O(1)
+    function pointerFunc(head: ListNode | null): boolean {
+        let slow = head;
+        let fast = head;
+        while (fast && fast.next) {
+            slow = slow.next;
+            fast = fast.next.next;
+
+            if (slow === fast) return true;
+        }
+        return false;
+    }
+}