Notebook

83. Remove Duplicates from Sorted List

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

Example 1:

Input: head = [1,1,2]
Output: [1,2]

Example 2:

Input: head = [1,1,2,3,3]
Output: [1,2,3]

Constraints:

The number of nodes in the list is in the range [0, 300].
-100 <= Node.val <= 100
The list is guaranteed to be sorted in ascending order.

Source

In [1]:

# Definition for singly-linked list.
class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next

Code

In [2]:

def delete_duplicates(head):
    if not head:
        return None
    newHead = head
    while newHead.next:
        if newHead.val == newHead.next.val:
            newHead.next = newHead.next.next
        else:
            newHead = newHead.next
    return head