Java [Leetcode 83]Remove Duplicates from Sorted List

题目描述：

Given a sorted linked list, delete all duplicates such that each element appear only once.

For example,
Given 1->1->2, return 1->2.
Given 1->1->2->3->3, return 1->2->3.

代码如下：

代码一，正常解法：

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode deleteDuplicates(ListNode head) {
    	if(head == null)
    		return null;
        ListNode cur = head.next;
        ListNode pre = head;
        while(cur != null){
        	if(cur.val == pre.val){
        		if(cur.next != null){
        			cur.val = cur.next.val;
        			cur.next = cur.next.next;
        		}else{
        			pre.next = null;
        			cur = null;
        		}
        	} else {
        		pre = cur;
        		cur = cur.next;
        	}
        }
        return head;
    }
}

思路二，递归解法：

public ListNode deleteDuplicates(ListNode head) {
        if(head == null || head.next == null)return head;
        head.next = deleteDuplicates(head.next);
        return head.val == head.next.val ? head.next : head;
}