Remove Duplicates In Sorted Linked List

Introduction

Removing duplicates from a sorted linked list is a common problem in data structures. Since the list is already sorted, duplicate elements appear next to each other, making it easier to remove them.

---

Problem Statement

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

---

Approach

We can solve this problem using a simple traversal:

1. Start from the head of the linked list
2. Compare current node with the next node
3. If both values are equal → skip the next node
4. Move to the next node
5. Repeat until the end of the list

---

Python Code

python
class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next

def deleteDuplicates(head):
    current = head

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

    return head

## Example:

    Input
1 -> 1 -> 2 -> 2 -> 3 -> 3

   ouput
1 -> 2 -> 3