[Leetcode][python]删除排序链表中的重复元素/删除排序链表中的重复元素 II

class Solution(object):
    def deleteDuplicates(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        if head == None or head.next == None:
            return head
        p = head
        while p.next:
            if p.next.val == p.val:
                p.next = p.next.next
            else:
                p = p.next
        return head

class Solution(object):
    def deleteDuplicates(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        if head == None:
            return head
        dummy = ListNode(-1)
        dummy.next = head
        p = dummy
        temp = head
        while p.next:
            while temp.next and temp.next.val == p.next.val:
                temp = temp.next
            if temp == p.next:  # 如果p.next temp相等，说明并没有重复，两个都进一位
                p = p.next
                temp = p.next
            else:  # 如果p.next和temp不相等，说明temp已经跑到很后面了（至少大两位），所以需要将p直接指向temp.next
                p.next = temp.next
        return dummy.next