linked list cycle solved

Author: mintheon

linked-list-cycle/mintheon.java

@@ -0,0 +1,28 @@
+/**
+ * Definition for singly-linked list.
+ * class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode(int x) {
+ *         val = x;
+ *         next = null;
+ *     }
+ * }
+ */
+//시간복잡도: O(n)
+//공간복잡도: O(1)
+public class Solution {
+  public boolean hasCycle(ListNode head) {
+    ListNode slow = head;
+    ListNode fast = head;
+
+    while(fast != null && fast.next != null) {
+      slow = slow.next;
+      fast = fast.next.next;
+
+      if(slow == fast) return true;
+    }
+
+    return false;
+  }
+}