How hard is LeetCode 83. Remove Duplicates from Sorted List?

LeetCode 83. Remove Duplicates from Sorted List is rated Easy on LeetCode.

What is the time complexity of LeetCode 83. Remove Duplicates from Sorted List?

The Python solution on this page runs in O(n), where n is the length of the linked list.

What is the space complexity of LeetCode 83. Remove Duplicates from Sorted List?

The Python solution on this page uses O(1) auxiliary space.

What topics does LeetCode 83. Remove Duplicates from Sorted List cover?

LeetCode 83. Remove Duplicates from Sorted List is tagged Linked List on LeetCode.

Remove Duplicates from Sorted List — LeetCode 83 Python Solution

EasyLinked List

Problem: #83
Pattern: Linked List
Reading time: 2 min
Source: leetcode.com

The problem

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

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

Python solution

Python

# 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]:
        cur = head
        while cur and cur.next:
            if cur.val == cur.next.val:
                cur.next = cur.next.next
            else:
                cur = cur.next
        return head

Complexity

Measure	Complexity
Time	O(n), where n is the length of the linked list
Space	O(1) auxiliary

Pattern: Linked List

Rewire pointers in place, with a dummy head and a saved next to keep it safe. LeetCode 83. Remove Duplicates from Sorted List is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Linked List.

The linked list guide has the Python template for the pattern and the 75 LeetCode problems that use it.

Frequently asked questions

How hard is LeetCode 83. Remove Duplicates from Sorted List?: LeetCode 83. Remove Duplicates from Sorted List is rated Easy on LeetCode.
What is the time complexity of LeetCode 83. Remove Duplicates from Sorted List?: The Python solution on this page runs in O(n), where n is the length of the linked list.
What is the space complexity of LeetCode 83. Remove Duplicates from Sorted List?: The Python solution on this page uses O(1) auxiliary space.
What topics does LeetCode 83. Remove Duplicates from Sorted List cover?: LeetCode 83. Remove Duplicates from Sorted List is tagged Linked List on LeetCode.