Remove Duplicates from Sorted Linked List

Hi everyone!
Today I solved a linked list problem where we need to remove duplicate nodes from a sorted list. Since the list is already sorted, the solution becomes much easier.

Problem
Given a sorted linked list, remove duplicate nodes so that each element appears only once.

Example:
Input: 2 -> 2 -> 4 -> 5

Output: 2 -> 4 -> 5

My Approach
At first, I thought of using a set to track duplicates, but that would use extra space.
Then I realized:

Since the list is sorted, duplicates will always be next to each other
So we can solve it in-place.

Logic
Traverse the linked list
Compare current node with next node:
If equal → remove next node
Else → move forward

Code (Python)
def removeDuplicates(head):
curr = head

while curr and curr.next:
    if curr.data == curr.next.data:
        curr.next = curr.next.next
    else:
        curr = curr.next

return head

Time & Space Complexity
Time: O(n)
Space: O(1)

Key Insight
Because the list is sorted, duplicates are always adjacent — no need for extra memory.

What I Learned
Sorted property can simplify problems
Linked list manipulation requires careful pointer updates
In-place solutions are more efficient

Thanks for reading!
Feel free to share other approaches or improvements.