Remove Duplicates from Sorted List

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

Example 1:

Input: 1->1->2
Output: 1->2

Example 2:

Input: 1->1->2->3->3
Output: 1->2->3

第一想法是转 list 再转链表

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

class Solution(object):
    def deleteDuplicates(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        s = []
        while head:
            if head.val not in s:
                s.append(head.val)
            head = head.next
        
        dummy = current = ListNode(None)
        for i in s:
            current.next = ListNode(i)
            current = current.next
        
        return dummy.next

回头再审下题，给了一个排好序的链表，这题考的操作链表的能力

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

class Solution(object):
    def deleteDuplicates(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        current = head
        
        while current is not None and current.next is not None:
            if current.val == current.next.val:
                current.next = current.next.next
            else:
                current = current.next
            
        return head

考虑清楚后再动手，比较快，着急只会起反作用

难度降低后快了很多，可是成就感低了很多

慢就是快