feat: 문제풀이 추가

Author: JEONGHWANMIN

linked-list-cycle/hwanmini.js

@@ -0,0 +1,29 @@
+// 시간복잡도: O(n)
+// 공간복잡도: O(1)
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val) {
+ *     this.val = val;
+ *     this.next = null;
+ * }
+ */
+
+/**
+ * @param {ListNode} head
+ * @return {boolean}
+ */
+var hasCycle = function(head) {
+    let fastPointer = head;
+    let slowPointer = head;
+
+    while (fastPointer && fastPointer.next) {
+        slowPointer = slowPointer.next;
+        fastPointer = fastPointer.next.next
+
+        if (fastPointer === slowPointer) return true
+
+    }
+
+    return false
+};