[Leetcode] Remove Duplicates from Sorted List

Remove Duplicates from Sorted List

 

Given a sorted linked list, delete all duplicates such that each element appear only once.

For example,
Given 1->1->2, return 1->2.
Given 1->1->2->3->3, return 1->2->3.

Solution:

Approach: "Building-block" methods: basic operation - Deleting node

current.next = current.next.next # remove 2nd duplicated node

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

class Solution:
    # @param head, a ListNode
    # @return a ListNode
    def deleteDuplicates(self, head):
        #迭代版，时间复杂度O(n)，空间复杂度O(1)
        current = head
        while current and current.next:
            if current.val == current.next.val:
                current.next = current.next.next # remove 2nd duplicated node
            else:
                current = current.next
        return head