Detect cycle in linked list

gistfile1.java

private static boolean detectCycle(ListNode head) {
		ListNode p1 = head;
		ListNode p2 = head;
 
		while (p2 != null && p2.next != null) {
			p1 = p1.next;
			p2 = p2.next.next;
			if (p1 == p2)
				return true;
		}
 
		return false;
	}