Merge pull request #184 from pablo9891/master

Rename binary_search_tree and added a getNode function

Author: harshildarji

Diff for: data_structures/Binary Tree/binary_seach_tree.py

@@ -0,0 +1,130 @@
+'''
+A binary search Tree
+'''
+
+class Node:
+
+    def __init__(self, label):
+        self.label = label
+        self.left = None
+        self.right = None
+
+    def getLabel(self):
+        return self.label
+
+    def setLabel(self, label):
+        self.label = label
+
+    def getLeft(self):
+        return self.left
+
+    def setLeft(self, left):
+        self.left = left
+
+    def getRight(self):
+        return self.right
+
+    def setRight(self, right):
+        self.right = right
+
+
+class BinarySearchTree:
+
+    def __init__(self):
+        self.root = None
+
+    def insert(self, label):
+        # Create a new Node
+        new_node = Node(label)
+        # 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:
+                #We keep reference of the parent node
+                parent_node = curr_node
+                #If node label is less than current node
+                if new_node.getLabel() < curr_node.getLabel():
+                #We go left
+                    curr_node = curr_node.getLeft()
+                else:
+                    #Else we go right
+                    curr_node = curr_node.getRight()
+            #We insert the new node in a leaf
+            if new_node.getLabel() < parent_node.getLabel():
+                parent_node.setLeft(new_node)
+            else:
+                parent_node.setRight(new_node)        
+    
+    def getNode(self, label):
+        curr_node = None
+        #If the tree is not empty
+        if(not self.empty()):
+            #Get tree root
+            curr_node = self.getRoot()
+            #While we don't find the node we look for
+            #I am using lazy evaluation here to avoid NoneType Attribute error
+            while curr_node is not None and curr_node.getLabel() is not label:
+                #If node label is less than current node
+                if label < curr_node.getLabel():
+                    #We go left
+                    curr_node = curr_node.getLeft()
+                else:
+                    #Else we go right
+                    curr_node = curr_node.getRight()
+        return curr_node
+
+    def empty(self):
+        if self.root is None:
+            return True
+        return False
+
+    def preShow(self, curr_node):
+        if curr_node is not None:
+            print(curr_node.getLabel())
+            self.preShow(curr_node.getLeft())
+            self.preShow(curr_node.getRight())
+
+    def getRoot(self):
+        return self.root
+
+'''
+Example
+            8
+           / \
+          3   10
+         / \    \
+        1   6    14
+           / \   /
+          4   7 13 
+'''
+
+
+if __name__ == "__main__":
+    t = BinarySearchTree()
+    t.insert(8)
+    t.insert(3)
+    t.insert(1)
+    t.insert(6)
+    t.insert(4)
+    t.insert(7)
+    t.insert(10)
+    t.insert(14)
+    t.insert(13)
+
+    t.preShow(t.getRoot())
+
+    if(t.getNode(6) is not None):
+        print("The label 6 exists")
+    else:
+        print("The label 6 doesn't exist")
+
+    if(t.getNode(-1) is not None):
+        print("The label -1 exists")
+    else:
+        print("The label -1 doesn't exist")
+