CA 23 - Remove duplicates from a sorted linked list

#algorithms #beginners #computerscience #tutorial

Problem Statement

Given a sorted singly linked list, remove duplicates (nodes with duplicate values) such that each element appears only once.

Note: Try not to use extra space. The linked list is already sorted.

Examples:

Input: 2 → 2 → 4 → 5
Output: 2 → 4 → 5

Input: 2 → 2 → 2 → 2 → 2
Output: 2

My Goal

For this problem, my goal was to:

Understand how duplicates appear in sorted linked lists
Remove duplicates without using extra memory
Traverse and modify linked list efficiently
Strengthen pointer manipulation skills

My Approach & Solution

I used a single traversal approach since the list is already sorted.

Idea:

Traverse the list using a pointer
Compare current node with next node
If values are same:
Skip the next node
Else:
Move forward

Solution Code (Python)

class ListNode:
    def __init__(s, v=0, n=None):
        s.val = v
        s.next = n

def deleteDuplicates(h):
    c = h

    while c and c.next:
        if c.val == c.next.val:
            c.next = c.next.next
        else:
            c = c.next

    return h