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Merge pull request #200 from pablo9891/master

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Added delete function to binary_search_tree.py and print function
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Harshil 2017-10-31 10:43:47 +05:30 committed by GitHub
commit 9dfd0a6e73
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1 changed files with 151 additions and 24 deletions
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175
data_structures/Binary Tree/binary_search_tree.py
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@ -1,13 +1,14 @@
'''
A binary search Tree
'''
class Node:
def __init__(self, label):
def __init__(self, label, parent):
self.label = label
self.left = None
self.right = None
#Added in order to delete a node easier
self.parent = parent
def getLabel(self):
return self.label
@ -27,6 +28,11 @@ class Node:
def setRight(self, right):
self.right = right
def getParent(self):
return self.parent
def setParent(self, parent):
self.parent = parent
class BinarySearchTree:
@ -35,13 +41,12 @@ class BinarySearchTree:
def insert(self, label):
# Create a new Node
new_node = Node(label)
new_node = Node(label, None)
# If Tree is empty
if self.empty():
self.root = new_node
else:
#If Tree is not empty
parent_node = None
curr_node = self.root
#While we don't get to a leaf
while curr_node is not None:
@ -58,7 +63,34 @@ class BinarySearchTree:
if new_node.getLabel() < parent_node.getLabel():
parent_node.setLeft(new_node)
else:
parent_node.setRight(new_node)
parent_node.setRight(new_node)
#Set parent to the new node
new_node.setParent(parent_node)
def delete(self, label):
if (not self.empty()):
#Look for the node with that label
node = self.getNode(label)
#If the node exists
if(node is not None):
#If it has no children
if(node.getLeft() is None and node.getRight() is None):
self.__reassignNodes(node, None)
node = None
#Has only right children
elif(node.getLeft() is None and node.getRight() is not None):
self.__reassignNodes(node, node.getRight())
#Has only left children
elif(node.getLeft() is not None and node.getRight() is None):
self.__reassignNodes(node, node.getLeft())
#Has two children
else:
#Gets the max value of the left branch
tmpNode = self.getMax(node.getLeft())
#Deletes the tmpNode
self.delete(tmpNode.getLabel())
#Assigns the value to the node to delete and keesp tree structure
node.setLabel(tmpNode.getLabel())
def getNode(self, label):
curr_node = None
@ -78,45 +110,121 @@ class BinarySearchTree:
curr_node = curr_node.getRight()
return curr_node
def getMax(self, root = None):
if(root is not None):
curr_node = root
else:
#We go deep on the right branch
curr_node = self.getRoot()
if(not self.empty()):
while(curr_node.getRight() is not None):
curr_node = curr_node.getRight()
return curr_node
def getMin(self, root = None):
if(root is not None):
curr_node = root
else:
#We go deep on the left branch
curr_node = self.getRoot()
if(not self.empty()):
curr_node = self.getRoot()
while(curr_node.getLeft() is not None):
curr_node = curr_node.getLeft()
return curr_node
def empty(self):
if self.root is None:
return True
return False
def preShow(self, curr_node):
def __InOrderTraversal(self, curr_node):
nodeList = []
if curr_node is not None:
print(curr_node.getLabel())
self.preShow(curr_node.getLeft())
self.preShow(curr_node.getRight())
nodeList.insert(0, curr_node)
nodeList = nodeList + self.__InOrderTraversal(curr_node.getLeft())
nodeList = nodeList + self.__InOrderTraversal(curr_node.getRight())
return nodeList
def getRoot(self):
return self.root
'''
Example
8
/ \
3 10
/ \ \
1 6 14
/ \ /
4 7 13
'''
def __isRightChildren(self, node):
if(node == node.getParent().getRight()):
return True
return False
def __reassignNodes(self, node, newChildren):
if(newChildren is not None):
newChildren.setParent(node.getParent())
if(node.getParent() is not None):
#If it is the Right Children
if(self.__isRightChildren(node)):
node.getParent().setRight(newChildren)
else:
#Else it is the left children
node.getParent().setLeft(newChildren)
if __name__ == "__main__":
#This function traversal the tree. By default it returns an
#In order traversal list. You can pass a function to traversal
#The tree as needed by client code
def traversalTree(self, traversalFunction = None, root = None):
if(traversalFunction is None):
#Returns a list of nodes in preOrder by default
return self.__InOrderTraversal(self.root)
else:
#Returns a list of nodes in the order that the users wants to
return traversalFunction(self.root)
#Returns an string of all the nodes labels in the list
#In Order Traversal
def __str__(self):
list = self.__InOrderTraversal(self.root)
str = ""
for x in list:
str = str + " " + x.getLabel().__str__()
return str
def InPreOrder(curr_node):
nodeList = []
if curr_node is not None:
nodeList = nodeList + InPreOrder(curr_node.getLeft())
nodeList.insert(0, curr_node.getLabel())
nodeList = nodeList + InPreOrder(curr_node.getRight())
return nodeList
def testBinarySearchTree():
'''
Example
8
/ \
3 10
/ \ \
1 6 14
/ \ /
4 7 13
'''
'''
Example After Deletion
7
/ \
1 4
'''
t = BinarySearchTree()
t.insert(8)
t.insert(3)
t.insert(1)
t.insert(6)
t.insert(4)
t.insert(7)
t.insert(1)
t.insert(10)
t.insert(14)
t.insert(13)
t.insert(4)
t.insert(7)
t.preShow(t.getRoot())
#Prints all the elements of the list in order traversal
print(t.__str__())
if(t.getNode(6) is not None):
print("The label 6 exists")
@ -128,3 +236,22 @@ if __name__ == "__main__":
else:
print("The label -1 doesn't exist")
if(not t.empty()):
print("Max Value: ", t.getMax().getLabel())
print("Min Value: ", t.getMin().getLabel())
t.delete(13)
t.delete(10)
t.delete(8)
t.delete(3)
t.delete(6)
t.delete(14)
#Gets all the elements of the tree In pre order
#And it prints them
list = t.traversalTree(InPreOrder, t.root)
for x in list:
print(x)
if __name__ == "__main__":
testBinarySearchTree()