[Leetcode/Linked List]83. Remove Duplicates from Sorted List

Solution 1: prev + curr

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def deleteDuplicates(self, head: Optional[ListNode]) -> Optional[ListNode]:
        prev = head
        curr = None
        if head:
            curr = head.next
        
        while curr:
            if curr.val == prev.val:
                curr = curr.next
                prev.next = curr
            else:
                prev = curr
                curr = curr.next
        
        return head

Solution 2: Only curr

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def deleteDuplicates(self, head: Optional[ListNode]) -> Optional[ListNode]:
        curr = head
        while curr and curr.next:
            if curr.val == curr.next.val:
                curr.next = curr.next.next  # Skip duplicate
            else:
                curr = curr.next
        return head