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Commit 1720188

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day3:level order tree traversals
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‎README.md

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| Current Status| Stats |
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| :------------: | :----------: |
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| Total C++ Problems | 188 |
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| Total Python Problems | 6 |
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| Current Daily Streak| 2 |
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| Total Python Problems | 8 |
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| Current Daily Streak| 3 |
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| Last Streak | 06/20/2019 - 06/21/2019|
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| Current Streak | 06/23/2019 - 06/24/2019|
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| Current Streak | 06/23/2019 - 06/25/2019|
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</center>
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### Tree Problems
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| Problem | Solution |
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| :------------ | :----------: |
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|Iterative Level order traversal of Tree using queue |[levelOrderTraversalIterative.cpp](tree_problems/levelOrderTraversalIterative.cpp)|
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|Recursive Level order traveral of Tree | [levelOrderTraversalRecursive.cpp](tree_problems/levelOrderTraversalRecursive.cpp)|
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|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)|
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|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)|
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|ZigZag Traversal of Tree | [zigZagTraversal.cpp](tree_problems/zigZagTraversal.cpp)|
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|Predecessor and Successor of a given node in Binary Search Tree | [predecessorSuccessor.cpp](tree_problems/predecessorSuccessor.cpp)|
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|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)|
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# Program to implement level order traversal - recursive version
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class TreeNode:
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"""Representation of a binary tree node"""
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def __init__(self, data):
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self.data = data
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self.left = None
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self.right = None
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class Tree:
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"""Representation of a binary tree"""
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def __init__(self):
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self.root = None
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def in_order(self):
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"""In order traversal of the tree"""
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current = self.root
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stack = []
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done = False
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while not done:
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if current is not None:
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stack.append(current)
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current = current.left
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elif stack:
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current = stack.pop()
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print(current.data, end=' ')
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current = current.right
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else:
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done = True
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print()
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def level_order(self):
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"""Prints level order tree traversal iterative way"""
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#an empty queue
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queue = []
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queue.append(self.root)
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while queue:
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curr = queue.pop(0)
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print(curr.data, end=' ')
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if curr.left:
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queue.append(curr.left)
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if curr.right:
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queue.append(curr.right)
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print()
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if __name__ == "__main__":
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tree = Tree()
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tree.root = TreeNode(1)
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tree.root.left = TreeNode(2)
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tree.root.right = TreeNode(3)
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tree.root.left.left = TreeNode(4)
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tree.root.left.right = TreeNode(5)
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tree.root.right.left = TreeNode(6)
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tree.root.right.right = TreeNode(7)
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print("Inorder: ")
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tree.in_order()
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print("Level order:")
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tree.level_order()
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# Program to implement level order traversal - recursive version
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class TreeNode:
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"""Representation of a binary tree node"""
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def __init__(self, data):
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self.data = data
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self.left = None
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self.right = None
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class Tree:
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"""Representation of a binary tree"""
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def __init__(self):
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self.root = None
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def in_order(self):
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"""In order traversal of the tree"""
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current = self.root
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stack = []
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done = False
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while not done:
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if current is not None:
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stack.append(current)
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current = current.left
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elif stack:
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current = stack.pop()
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print(current.data, end=' ')
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current = current.right
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else:
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done = True
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print()
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def height_util(self, node):
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"""Utility function for recursive calculation of the height of the tree"""
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if not node:
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return 0
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else:
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lheight = self.height_util(node.left)
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rheight = self.height_util(node.right)
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return lheight+1 if lheight > rheight else rheight + 1
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def height(self):
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"""Height of the tree"""
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return self.height_util(self.root)
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def print_level(self, node, level):
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"""Prints current level of the tree"""
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if not node:
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return
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if level == 1:
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print(node.data, end=' ')
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elif level > 1:
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self.print_level(node.left, level-1)
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self.print_level(node.right, level-1)
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def level_order(self):
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"""Print level order traversal of the tree in recursive manner"""
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h = self.height()
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for i in range(1, h+1):
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self.print_level(self.root, i)
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if __name__ == "__main__":
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tree = Tree()
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tree.root = TreeNode(1)
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tree.root.left = TreeNode(2)
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tree.root.right = TreeNode(3)
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tree.root.left.left = TreeNode(4)
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tree.root.left.right = TreeNode(5)
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tree.root.right.left = TreeNode(6)
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tree.root.right.right = TreeNode(7)
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print("Inorder: ")
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tree.in_order()
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print("Level order:")
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tree.level_order()
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print()

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