Remove Duplicates in Linked List | Dataford Interview Questions

For a linked-list processing component used in Zensar Technologies solutions, remove duplicate values from a singly linked list. The input may be sorted or unsorted, and the relative order of retained nodes must remain unchanged.

Implement remove_duplicates(head, is_sorted) and return the updated head. When is_sorted is True, equal values are adjacent. When it is False, duplicates may occur anywhere, so retain only the first occurrence of each value.

Assume the following node structure is available:

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

The test cases serialize a linked list as an array of node values. The evaluator converts the array to a linked list before calling the function and serializes the returned list for comparison.

Constraints

0 <= n <= 10^5
-10^9 <= node.val <= 10^9
The list is singly linked
A sorted input is nondecreasing
The first occurrence of each value must be preserved

Function Signature

def remove_duplicates(head, is_sorted):

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