1, 题目

给定一个排序链表，删除所有重复的元素，使得每个元素只出现一次。

示例 1:

  1. 输入: 1->1->2
  2. 输出: 1->2

示例 2:

输入: 1->1->2->3->3
输出: 1->2->3

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/remove-duplicates-from-sorted-list
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

2, 算法

#scala
object Solution {
    def deleteDuplicates(head: ListNode): ListNode = {
        if (head == null) {
            return head
        }
        var current = head
        var current_next = current.next
        while (current_next != null) {
            while (current_next != null && current.x == current_next.x) {
                current.next = current_next.next
                current_next.next = null
                current_next = current.next
            }
            if (current_next != null) {
                current = current_next
                current_next = current.next
            }
        }
        head
    }
}

#python
class Solution:
    def deleteDuplicates(self, head: ListNode) -> ListNode:
        if head is None:
            return head
        current = head
        current_next: ListNode = current.next
        while current_next is not None:
            while current_next is not None and current.val == current_next.val:
                current.next = current_next.next
                current_next.next = None
                current_next = current.next
            if current_next is not None:
                current = current_next
                current_next = current.next
        return head