Solution 7: 判断两链表是否相交

public class ListIntersection {
	// two single list
	public boolean isIntersectionOfTwoSingleList(ListNode l1, ListNode l2) {
		if (l1 == null || l2 == null) {
			return false;
		}

		// whether the end of two list is same
		ListNode endOfList1 = getEndOfList(l1);
		ListNode endOfList2 = getEndOfList(l2);

		return endOfList1 == endOfList2;
	}

	private ListNode getEndOfList(ListNode head) {
		if (head == null) {
			return null;
		}

		ListNode node = head;
		while (node.next != null) {
			node = node.next;
		}
		return node;
	}

	// two list with cycle
	public boolean isIntersectionOfTwoListWithCycle(ListNode l1, ListNode l2) {
		if (l1 == null || l2 == null) {
			return false;
		}

		ListNode slow = l1, fast = l2;

		while (fast.next != null || fast != null || slow != null) {
			slow = slow.next;
			fast = fast.next.next;
			if (slow == fast) {
				return true;
			}
		}

		return false;
	}
}