new_contents: # Definition for singly-linked list.
  # class ListNode:
  #     def __init__(self, x):
  #         self.val = x
  #         self.next = None
  
  class Solution:
      # @param {ListNode} head
      # @return {ListNode}
      def deleteDuplicates(self, head):
          if head == None:
              return None
          t = {}
          p = head
          while p != None:
              if p.val not in t:
                  t[p.val] = False
              else:
                  t[p.val] = True
              p = p.next
          dump = ListNode(0)
          dump.next = head
          p = dump
          while p.next != None:
              if t[p.next.val]:
                  p.next = p.next.next
              else:
                  p = p.next
          return dump.next
  
subject: Create RmDupFrSortedLst2_001.py