Tree

What is leaf node in binary tree?
A node in a binary tree which do not have any child nodes is called leaf node. The leaf node do not have any children i.e. left and right reference both null. We have to count the number of leaf nodes in the binary tree. In other ways we need to find out all the nodes in the binary tree which do not have any children (both right node and left node null).
So as per our problem statement, we have to iterate over the binary tree and find the number of leaf nodes in the binary tree.

We are given the Binary Tree, we need to find the maximum element in the Binary Tree. Suppose we have following tree, As per the problem statement we have to iterate over the binary tree and find the maximum element in the binary tree.

What is level in binary tree?
As per the definition of binary tree is one, where each node has, at most, 2 children. Each node can have left and right child. The root of the tree, is at level 0. Root’s children are at level 1, etc.
As an example, consider the tree:

We have to calculate the sum of all the nodes in a binary tree. To get the sum of all nodes in binary tree, we need to traverse the whole binary tree and while traversing we can start adding the sum of each node.

Let us define the problem statement, before we start our discussion about calculating the height of binary tree. What is height of Binary tree? Conventionally, the longest path from root to deepest leaf node define the height of binary tree.

Binary tree traversal using level order traversal or breadth first search non recursive algorithm in java (example). Visit root to leaf node level wise.