Remove Duplicates from Sorted Linked List

83. Remove Duplicates from Sorted List

Easy

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] 

Constraints:

• 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 self.next = next class Solution: def deleteDuplicates(self, head: Optional[ListNode]) -> Optional[ListNode]: current = head if head is None: return None while current.next: if current.val == current.next.val: next_element = current.next.next current.next = next_element else: current = current.next return head #end 

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