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Tree Introduction


  1. Tree
  2. Degree,Leafnode
  3. Parent-child node
  4. Ancestors and Descendants
  5. Level number Height


  1. A tree is defined as a finite set of one or more data items (nodes) ,such that :
  2. There is a special node called the root node of the tree
  3. The remaining nodes are partitioned into n≥o disjoint subsets ,each of which is itself a tree, and they are called subtrees

What Is A Tree In Real World?

  • A tree is a non-linear data structure ,which is used to represent hierarchical relationship existing among several data items


  • The number of subtrees of a node is called its degree.

Leaf Node

  • A node with degree zero is
    called leaf.
  • The leaf nodes are also called
    terminal nodes .

Parent -children

  • If  R is a root node and its subtrees are T1,T2,T3  and root of the subtrees are R1,R2,R3,then R1,R2,R3 are called children of R and R  is called parent od R1,R2,R3

Siblings & Degree of Tree

  • children of the same parent are called Siblings
  • The degree of the tree is maximum degree of the nodes in the tree

Ancestors and Descendants

  • The ancestors of a node are all the nodes along the path from the root to that node .
  • The descendants of a node are all the nodes along the path from node to terminal node.

Level Number

  • Each node is assigned a level
  • The root node of the tree is
    assigned a level number 0.
  • Every other node assign a
    level number which is one more than the level number of its parent.

Level Number:


  • Nodes with the same level number are said to belong to the same

Height or Depth

  • The height or depth of a tree is the maximum number of nodes in a branch
  • A line drawn from a node to its
    children is called an edge
  • Sequence of consecutive edges is called path
  • Path ending in a leaf is called a branch