LinkedListCycle.java

src/LinkedListCycle.java

@@ -0,0 +1,27 @@
+package ListNode;
+/**
+ * 
+ * @author chenqun
+ * Given a linked list, determine if it has a cycle in it.
+ * Follow up:Can you solve it without using extra space?
+ */
+//우찹寧濾，우寧濾浬좃홀宅찹寧濾宮島
+public class LinkedListCycle {
+
+	public boolean hasCycle(ListNode head){
+		if(head == null) return false;
+		ListNode fast = head.next;
+		ListNode slow = head;
+		while( fast != slow){
+			if(fast == null || fast.next == null) return false;
+			fast = fast.next.next;
+			slow = slow.next;
+		}
+		return true;
+	}
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+
+	}
+
+}