What is binary tree and how is it different then other trees?

Question

Given a binary tree print it in inward spiral order i.e first print level 1, then level n, then level 2, then n-1 and so on.

For Ex -

         1 
   2           3 
 4    5       6     7 
8 9  10 11  12 13  14 15 

Print- 1 15 14 13 12 11 10 9 8 2 3 7 6 5 4

Answer 1

Lets understand what is Tree Data Structure first as it it important to know what is tree to know what is binary Tree -

Tree is a graph without any loop/circuit, where we have exactly one way to connect two nodes. In the implementation form a tree is a abstract data type (ADT) that simulates a hierarchical tree structure, with a root value and subtrees of children with a parent node, represented as a set of linked nodes. Following are the tree terminology -
Root – The top node in a tree.
Parent – The converse notion of a child.
Siblings – Nodes with the same parent.
Descendant – A node reachable by repeated proceeding from parent to child.
Ancestor – A node reachable by repeated proceeding from child to parent.
Leaf – A node with no children.
Internal node – A node with at least one child.
External node – A node with no children.
Degree – Number of sub trees of a node.
Edge – Connection between one node to another.
Path – A sequence of nodes and edges connecting a node with a descendant.
Level – The level of a node is defined by 1 + (the number of connections between the node and the root).
Height of node – The height of a node is the number of edges on the longest downward path between that node and a leaf.
Height of tree – The height of a tree is the height of its root node.
Depth – The depth of a node is the number of edges from the node to the tree's root node.
Forest – A forest is a set of n ≥ 0 disjoint trees.

Now coming to the Binary Tree -
A tree is called Binary tree when any node can have max two child (node). Example