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BST.py
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BST.py
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""" Binary Search Tree Implementation: search, insert, print methods. """
class Node(object):
def __init__(self, value):
self.value = value
self.left = None
self.right = None
class BST(object):
def __init__(self, root):
self.root = Node(root)
def insert(self, new_val):
return self.insert_helper(self.root,new_val)
def insert_helper(self,start,new_val):
"""
Helper function for recursive insert method.
"""
if new_val>start.value:
if start.right:
self.insert_helper(start.right,new_val)
else:
start.right = Node(new_val)
elif new_val<start.value:
if start.left:
self.insert_helper(start.left,new_val)
else:
start.left = Node(new_val)
def search(self, find_val):
return self.search_helper(self.root,find_val)
def search_helper(self, start, find_val):
"""
Helper function for recursive search method.
"""
if start:
if start.value == find_val:
return True
elif find_val>start.value:
return self.search_helper(start.right,find_val)
elif find_val<start.value:
return self.search_helper(start.left,find_val)
return False
def print_tree(self):
return self.print_helper(self.root)[:-1]
def print_helper(self,next,traversal =''):
"""
Helper function for recursive print method.
"""
if next:
traversal +=(str(next.value)+'-')
traversal = self.print_helper(next.left, traversal)
traversal = self.print_helper(next.right,traversal)
return traversal
"""
Test case:
# Set up tree
tree = BST(4)
# Insert elements
tree.insert(2)
tree.insert(1)
tree.insert(3)
tree.insert(5)
# Check search
# Should be True
print tree.search(4)
# Should be False
print tree.search(6)
"""