83.Remove Duplicates from Sorted List(E)

https://leetcode.com/problems/remove-duplicates-from-sorted-list/

1.Description(Easy)

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

Example

Given1->1->2, return1->2. Given1->1->2->3->3, return1->2->3.

2.Code

Version 1: 定义一个current指向head，直接遍历剔除即可。

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

        ListNode current=head;

        while(current.next!=null){

            if(current.val==current.next.val){
                current.next=current.next.next;
            }
            else{
            current=current.next;
            }
        }
        return head;
    }

Version 2: 快慢指针

其实和数组去重LeetBode 26 是一模一样的，唯一的区别是把数组赋值操作变成操作指针而已：

ListNode deleteDuplicates(ListNode head) {
    if (head == null) return null;
    ListNode slow = head, fast = head;
    while (fast != null) {
        if (fast.val != slow.val) {
            // nums[slow] = nums[fast];
            slow.next = fast;
            // slow++;
            slow = slow.next;
        }
        // fast++
        fast = fast.next;
    }
    // 断开与后面重复元素的连接
    slow.next = null;
    return head;
}