[leetcode]Remove Duplicates from Sorted List

Remove Duplicates from Sorted List

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.

 算法思路：

单次遍历，遇到后驱与自己一样，删掉，时间复杂度O(n)，空间O(1)。

public class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        if(head == null || head.next == null) return head;
        ListNode tail = head;
        while(tail.next != null){
            if(tail.next.val == tail.val){
                tail.next = tail.next.next;
            }else{
                tail = tail.next;
            }
        }
        return head;
    }
}