> For the complete documentation index, see [llms.txt](https://maksimdan.gitbook.io/interview-practice-problems/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://maksimdan.gitbook.io/interview-practice-problems/leetcode_sessions/83-remove-duplicates-from-sorted-list.md).

# 83 Remove Duplicates from Sorted List

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

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

**Complexity**: O(n) time, O(1) space

**The Idea**: Iterate through the list of elements, and map each pointer to skip past the same consecutive list of elements.

```python
# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
    def deleteDuplicates(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """

        iter = head
        while iter:
            temp_iter = iter.next
            while (temp_iter and iter.val == temp_iter.val):
                temp_iter = temp_iter.next
            iter.next = temp_iter
            iter = temp_iter

        return head
```