83. Remove Duplicates from Sorted List
EazyLeetCodeGiven 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
How to solve the problem
Code
Python
# 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]:
cur = head
if cur is None:
return head
while cur.next: # when the last node is not None
if cur.val == cur.next.val:
cur.next = cur.next.next
else:
cur = cur.next # cur++
return head
Complexity
- Time complexity: O(n)
- Space complexity: O(1)
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