checking node value exists in dictionary

Question

I am trying to write a snippet for removing duplicate elements in a linked list in python.

my condition of checking previous node values in dictionary is not yielding true. I am unable to figure out why it always returns false.

Node values are [ 0->1->2->2->3->4->4->5

def RemoveRepeatNode(self):
    curr_node = self.head
    unique_list = {}
    unique_list[curr_node.data] = 1

    while(curr_node.next != None):
        if curr_node.next.data in unique_list: ## doesn't evaluate to True
            print "repeated values ", curr_node.next.data
            curr_node = curr_node.next.next
        else:
            unique_list[curr_node.data] = 1
            curr_node = curr_node.next

Answer 1

Your if clause might be fine, but you do not relink. Change:

def RemoveRepeatNode(self):
    curr_node = self.head
    unique = {curr_node.data}  # better data structure: set

    while(curr_node.next != None):
        if curr_node.next.data in unique:
            curr_node.next = curr_node.next.next
            #        ^^^^^  relink!
        else:
            unique.add(curr_node.next.data) 
            # add .next.data         ^^^^^  that's the one you checked
            curr_node = curr_node.next