#=====================================================================
# Author: Isai Damier
# Title: In-order Traversal
# Project: geekviewpoint
# Package: algorithms
#
# Time Complexity of Solution:
# Best = Average = Worst = O(n).
#
# Description: visit left child; visit node; visit right child.
# This techniques visits a BST in sorted order.
#
# Technical Details:
# 0]preliminary check:
# 1) create stack
# 2] declare n and set it to self.root
# 3] while n is not None or stack is not empty
# 1) if n is not None THEN
# add n to stack and set n to n.left
# 2) ELSE pop stack into n, visit n, and set n to n.right
#
# Alternate Algorithm: recursive:
#
# def inorder(self):
# _inorder(self.root)
#
# def _inorder(self, n):
# if n is not None:
# _inorder(n.left)
# self.visit(n)
# _inorder(n.right)
#
#=====================================================================
from Queue import LifoQueue
class BST( object ):
def __init__( self ):
self.root = None
def getRoot( self ):
return self.root
def inorder( self ) :
n = self.root;
stack = LifoQueue()
while n is not None or not stack.empty():
if n is not None:
stack.put( n )
n = n.left
else:
n = stack.get() # pop last node added
self.visit( n )
n = n.right
import unittest
from algorithms.BST import BST
from cStringIO import StringIO
import sys
class Test( unittest.TestCase ):
#=====================================================================
# Test of inorder method, of class BST.
#=====================================================================
def testInorder( self ):
bst = BST()
treeTape = [200, 100, 300, 50, 150, 250, 350, 25, 75, 125,
175, 225, 275, 325, 375, 35, 212, 312, 400]
# add elements to tree
for i in treeTape:
bst.add( i )
self.assertEquals( len( treeTape ), bst.size() ) # has correct size
# test levelorder
old_stdout = sys.stdout
new_stdout = sys.stdout = StringIO()
bst.inorder() # assumes visit() prints to screen
treeTape.sort()
result = ( new_stdout.getvalue() ).split()
for i in range( len( treeTape ) ):
if treeTape[i] != int( result[i] ):
self.fail( "inorder traversal self.fails" )
self.assertEquals( len( treeTape ), bst.size() ) # has correct size
sys.stdout = old_stdout
print "done with testInorder"
