day3:level order tree traversals

Author: mandliya

README.md

@@ -7,10 +7,10 @@
 | Current Status|     Stats     |
 | :------------: | :----------: |
 | Total C++ Problems | 188 |
-| Total Python Problems | 6 |
-| Current Daily Streak| 2 |
+| Total Python Problems | 8 |
+| Current Daily Streak| 3 |
 | Last Streak | 06/20/2019 - 06/21/2019|
-| Current Streak | 06/23/2019 - 06/24/2019|
+| Current Streak | 06/23/2019 - 06/25/2019|
 
 </center>
 
@@ -115,8 +115,8 @@ Include contains single header implementation of data structures and some algori
 ### Tree Problems
 | Problem | Solution |
 | :------------ | :----------: |
-|Iterative Level order traversal of Tree using queue |[levelOrderTraversalIterative.cpp](tree_problems/levelOrderTraversalIterative.cpp)|
-|Recursive Level order traveral of Tree | [levelOrderTraversalRecursive.cpp](tree_problems/levelOrderTraversalRecursive.cpp)|
+|Iterative Level order traversal of Tree using queue |[levelOrderTraversalIterative.cpp](tree_problems/levelOrderTraversalIterative.cpp), [level_order_tree_traversal_iterative.py](tree_problems/level_order_tree_traversal_iterative.py)|
+|Recursive Level order traveral of Tree | [levelOrderTraversalRecursive.cpp](tree_problems/levelOrderTraversalRecursive.cpp), [level_order_tree_traversal_recursive.py](tree_problems/level_order_tree_traversal_recursive.py)|
 |ZigZag Traversal of Tree | [zigZagTraversal.cpp](tree_problems/zigZagTraversal.cpp)|
 |Predecessor and Successor of a given node in Binary Search Tree | [predecessorSuccessor.cpp](tree_problems/predecessorSuccessor.cpp)|
 |Given values of two nodes in a Binary Search Tree, find the Lowest Common Ancestor (LCA). Assume that both the values exist in the tree.| [lowest-common-ancestor.cpp](tree_problems/lowest-common-ancestor.cpp)|

tree_problems/level_order_tree_traversal_iterative.py

@@ -0,0 +1,63 @@
+# Program to implement level order traversal - recursive version
+
+class TreeNode:
+    """Representation of a binary tree node"""
+    def __init__(self, data):
+        self.data = data
+        self.left = None
+        self.right = None
+
+class Tree:
+    """Representation of a binary tree"""
+    def __init__(self):
+        self.root = None
+
+    def in_order(self):
+        """In order traversal of the tree"""
+        current = self.root
+        stack = []
+        done = False
+        while not done:
+            if current is not None:
+                stack.append(current)
+                current = current.left
+
+            elif stack:
+                current = stack.pop()
+                print(current.data, end=' ')
+                current = current.right
+            else:
+                done = True
+        print()
+
+    def level_order(self):
+        """Prints level order tree traversal iterative way"""
+        #an empty queue
+        queue = []
+        queue.append(self.root)
+        while queue:
+            curr = queue.pop(0)
+            print(curr.data, end=' ')
+            if curr.left:
+                queue.append(curr.left)
+            if curr.right:
+                queue.append(curr.right)
+        
+        print()
+
+
+if __name__ == "__main__":
+    tree = Tree()
+    tree.root = TreeNode(1)
+    tree.root.left = TreeNode(2)
+    tree.root.right = TreeNode(3)
+    tree.root.left.left = TreeNode(4)
+    tree.root.left.right = TreeNode(5)
+    tree.root.right.left = TreeNode(6)
+    tree.root.right.right = TreeNode(7)
+
+    print("Inorder: ")
+    tree.in_order()
+    print("Level order:")
+    tree.level_order()
+

tree_problems/level_order_tree_traversal_recursive.py

@@ -0,0 +1,79 @@
+# Program to implement level order traversal - recursive version
+
+class TreeNode:
+    """Representation of a binary tree node"""
+    def __init__(self, data):
+        self.data = data
+        self.left = None
+        self.right = None
+
+class Tree:
+    """Representation of a binary tree"""
+    def __init__(self):
+        self.root = None
+
+    def in_order(self):
+        """In order traversal of the tree"""
+        current = self.root
+        stack = []
+        done = False
+        while not done:
+            if current is not None:
+                stack.append(current)
+                current = current.left
+
+            elif stack:
+                current = stack.pop()
+                print(current.data, end=' ')
+                current = current.right
+            else:
+                done = True
+        print()
+
+    def height_util(self, node):
+        """Utility function for recursive calculation of the height of the tree"""
+        if not node:
+            return 0
+        else:
+            lheight = self.height_util(node.left)
+            rheight = self.height_util(node.right)
+            return lheight+1 if lheight > rheight else rheight + 1
+    
+    def height(self):
+        """Height of the tree"""
+        return self.height_util(self.root)
+        
+    def print_level(self, node, level):
+        """Prints current level of the tree"""
+        if not node:
+            return
+        if level == 1:
+            print(node.data, end=' ')
+        elif level > 1:
+            self.print_level(node.left, level-1)
+            self.print_level(node.right, level-1)
+    
+    def level_order(self):
+        """Print level order traversal of the tree in recursive manner"""
+        h = self.height()
+        for i in range(1, h+1):
+            self.print_level(self.root, i)
+
+
+
+if __name__ == "__main__":
+    tree = Tree()
+    tree.root = TreeNode(1)
+    tree.root.left = TreeNode(2)
+    tree.root.right = TreeNode(3)
+    tree.root.left.left = TreeNode(4)
+    tree.root.left.right = TreeNode(5)
+    tree.root.right.left = TreeNode(6)
+    tree.root.right.right = TreeNode(7)
+
+    print("Inorder: ")
+    tree.in_order()
+    print("Level order:")
+    tree.level_order()
+
+    print()