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