【剑指Offer学习】【题56：删除链表中重复的结点】

题目：
在一个排序的链表中，存在重复的结点，请删除该链表中重复的结点，重复的结点不保留，返回链表头指针。 例如，链表1->2->3->3->4->4->5 处理后为 1->2->5

思路：
利用递归的方式，依次进行判断

程序：

 class ListNode {
    int val;
    ListNode next = null;
    ListNode(int val) {
        this.val = val;
    }
}

public class subject56 {
	public static ListNode deleteDuplication(ListNode pHead) {
		if(pHead == null || pHead.next == null) {
			return pHead;
		}
		ListNode first = pHead;
		ListNode second = pHead.next;
		if(first.val == second.val) {//first是重复结点
			second = second.next;
			while(second != null && first.val == second.val) {
				second = second.next;
			}
			first = second;
			return deleteDuplication(first);//递归
		}else {//first不是重复结点
			first.next = deleteDuplication(second);//选择不是重复结点的结点作为下一个结点
			return first;
		}
	}
	public static void main(String args[]) {
		ListNode node1 = new ListNode(1);
		ListNode node2 = new ListNode(2);
		ListNode node3 = new ListNode(3);
		ListNode node4 = new ListNode(3);
		ListNode node5 = new ListNode(4);
		ListNode node6 = new ListNode(4);
		ListNode node7 = new ListNode(5);
		node1.next = node2;
		node2.next = node3;
		node3.next = node4;
		node4.next = node5;
		node5.next = node6;
		node6.next = node7;
		ListNode temp = deleteDuplication(node1);
		while(temp != null) {
			System.out.println(temp.val);
			temp = temp.next;
		}
	}
}