Binary tree is a special type of data structure. In binary tree, every node can have a maximum of 2 children, which are known as Left child and Right Child. It is a method of placing and locating the records in a database, especially when all the data is known to be in random access memory (RAM).
Definition:
"A tree in which every node can have maximum of two children is called as Binary Tree."
The above tree represents binary tree in which node A has two children B and C. Each children have one child namely D and E respectively.
Representation of Binary Tree using Array
Binary tree using array represents a node which is numbered sequentially level by level from left to right. Even empty nodes are numbered.
Array index is a value in tree nodes and array value gives to the parent node of that particular index or node. Value of the root node index is always -1 as there is no parent for root. When the data item of the tree is sorted in an array, the number appearing against the node will work as indexes of the node in an array.
Location number of an array is used to store the size of the tree. The first index of an array that is '0', stores the total number of nodes. All nodes are numbered from left to right level by level from top to bottom. In a tree, each node having an index i is put into the array as its i th element.
The above figure shows how a binary tree is represented as an array. Value '7' is the total number of nodes. If any node does not have any of its child, null value is stored at the corresponding index of the array.
