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Key error on python

  1. Dec 25, 2011 #1
    Hi everyone,
    I'm trying to implement the level-order for a binary tree with python (http://en.wikipedia.org/wiki/Tree_traversal)

    I wrote a first function bst that takes two arguments (integers a and b) and returns a binary tree with nodes a+b, a-b,a*b and a//b (when allowed)
    I tested this function and it seems to work.

    The problem I face is with my level-order function which takes a tree as an argument.
    I tried to use a queue here in order to get the level order.
    The problem is, when I call this function (on python shell), the following error is raised:

    line 96, in level_order
    KeyError: 'left'

    I tried to change a little bit my program to identify where this error comes from: I returned curr: no problem, I then returned curr['left'] and still no problem...

    If anyone has an idea...

    Attached Files:

  2. jcsd
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