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Isaac Tonyloi
Isaac Tonyloi

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Remove Duplicates from Sorted Linked List

83. Remove Duplicates from Sorted List


Given the head of a sorted linked list, delete all duplicates such that each element appears only once. Return the linked list sorted as well.


Example 1:

Input: head = [1,1,2]
Output: [1,2]

Example 2:

Input: head = [1,1,2,3,3]
Output: [1,2,3]



  • The number of nodes in the list is in the range [0, 300].
  • -100 <= Node.val <= 100
  • The list is guaranteed to be sorted in ascending order.

Python solution

# Definition for singly-linked list.
class ListNode:
     def __init__(self, val=0, next=None):
            self.val = val
   = next
class Solution:
    def deleteDuplicates(self, head: Optional[ListNode]) -> Optional[ListNode]:

        current = head

        if head is None:
            return None

            if current.val ==
                next_element =
       = next_element
                current =

        return head

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The time complexity of the above solution is O(n), where n is the total number of nodes in the linked list.

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