Tree is a hierarchical data structure that stores information in a parent-child relationship. There are different types of trees including binary trees, binary search trees, and expression trees. Binary trees restrict each node to having zero, one, or two children while binary search trees further require that all left descendants of a node are less than the node and all right descendants are greater than or equal. Expression trees represent mathematical expressions with operators as internal nodes and operands as leaves.

1. Data Structure Using C
Lecture:23,Trees: Overview of Trees, Terminology, Definitions:
Binary tree, Complete tree, Full Binary tree, Strictly Binary tree

2. Outline
• Overview of Trees,
• Terminology,
• Definitions:
– Binary tree,
– Complete tree,
– Binary tree,
– Strictly Binary tree

3. Tree
• Tree is a hierarchical data structure which
stores the information naturally in the form of
hierarchy style.
• Tree is one of the most powerful and
advanced data structures.
• It is a non-linear data structure compared to
arrays, linked lists, stack and queue.
• It represents the nodes connected by edges.

4. Example: The node A is the root node of the tree while the other nodes can
be seen as the children of A.

5. Basic terminology

6. Example:-

7. Levels of a node
• Levels of a node represents the number of
connections between the node and the
root.
• It represents generation of a node.
• If the root node is at level 0, its next node
is at level 1, its grand child is at level 2
and so on.

8. Example: Advantages of Tree

9. Note:
• If node has no children, it is
called Leaves or External Nodes.
• Nodes which are not leaves, are called Internal
Nodes. Internal nodes have at least one child.
• A tree can be empty with no nodes or a tree consists of
one node called the Root.

10. Height of a Node
Height of a Node: Example:-
• Height of a node is a
number of edges on
the longest path
between that node and
a leaf. Each node has
height.

11. Note:
• Height of a node defines the longest path
from the node to a leaf.
• Path can only be downward.

12. Depth of a Node: Example:-
• Depth, it is located at
top which is root level
and therefore we call
it depth of a node
Note: Depth of the
root is 0.

13. Static representation of tree
#define MAXNODE 500
struct treenode {
int root;
int father;
int son;
int next;
}

14. Dynamic representation of tree
struct treenode
{
int root;
struct treenode *father;
struct treenode *son
struct treenode *next;
}

15. Advantages of Tree
• Tree reflects structural relationships in the
data.
• It is used to represent hierarchies.
• It provides an efficient insertion and
searching operations.
• Trees are flexible. It allows to move
subtrees around with minimum effort.

16. Types of Tree
• The tree data structure can be classified
into six different categories.

18. General Tree
• General Tree stores the elements in a
hierarchical order in which the top level
element is always present at level 0 as the
root element.
• All the nodes except the root node are present
at number of levels.
• The nodes which are present on the same
level are called siblings while the nodes
which are present on the different levels
exhibit the parent-child relationship among
them.

19. Forests
• Forest can be defined as the set of
disjoint trees which can be obtained
by deleting the root node and the
edges which connects root node to
the first level node.

20. Example:-

21. Example:-

22. Binary Tree
• Binary tree is a data structure in which each
node can have at most 2 children.
• The node present at the top most level is called
the root node. A node with the 0 children is
called leaf node.
• Binary Trees are used in the applications like
expression evaluation and many more.

23. Binary Search Tree
• Binary search tree is an ordered binary tree.
• All the elements in the left sub-tree are less
than the root while elements present in the
right sub-tree are greater than or equal to the
root node element.
• Binary search trees are used in most of the
applications of computer science domain like
searching, sorting, etc.

24. Expression Tree
• Expression trees are used to evaluate the
simple arithmetic expressions. Expression tree
is basically a binary tree where internal nodes
are represented by operators while the leaf
nodes are represented by operands.
• Expression trees are widely used to solve
algebraic expressions like (a+b)*(a-b).

25. Q. Construct an expression tree by using the following algebraic expression.
(a + b) / (a*b - c) + d

26. Tournament Tree
• Tournament tree are used to record the winner
of the match in each round being played
between two players.
• Tournament tree can also be called as
selection tree or winner tree.
• External nodes represent the players among
which a match is being played while the
internal nodes represent the winner of the
match played.
• At the top most level, the winner of the
tournament is present as the root node of the
tree.

27. Example:-

28. Complete Tree
Example:-
• A Binary Tree is said to be
a complete binary tree if all
of the leaves are located at
the same level d. A
complete binary tree is a
binary tree that contains
exactly 2^l nodes at each
level between level 0 and d.
The total number of nodes
in a complete binary tree
with depth d is 2d+1-1 where
leaf nodes are 2d while non-
leaf nodes are 2d-1.

29. Full Binary tree Example:-
• A full binary tree
(sometimes proper
binary tree or 2-tree)
is a tree in which
every node other
than the leaves has
two children.

30. Strictly Binary tree
Example:-
• In Strictly Binary Tree,
every non-leaf node
contain non-empty left
and right sub-trees. In
other words, the degree
of every non-leaf node
will always be 2. A
strictly binary tree with
n leaves, will have (2n
- 1) nodes.