What Is Similar Tree in Data Structure?


Angela Bailey

In data structures, a similar tree is a concept that refers to two trees having the same structure. This means that both trees have the same arrangement of nodes and edges.

However, the values contained in these nodes may be different. Let’s delve deeper into understanding what a similar tree entails.

Definition of Similar Tree

A similar tree is defined as two binary trees that have the same structure, but their node values may vary. A binary tree consists of nodes, where each node contains a value and has at most two children – left child and right child.


To illustrate this concept, let’s consider two binary trees:

Tree 1:

  • Root: 5
  • Left Child: 3
  • Right Child: 8

Tree 2:

  • Root: 7
  • Left Child: 4
  • Right Child: 9

Determining Similarity Between Two Trees

To determine whether two trees are similar or not, we need to compare their structures. This can be done through a recursive algorithm that checks if each corresponding pair of nodes in the two trees have the same structure.

The algorithm can be defined as follows:

  1. If both trees are empty, they are considered similar.
  2. If both trees are non-empty:
    • a. Check if the values of the roots of both trees are equal.
    • b.

      Recursively check if the left subtrees of both trees are similar.

    • c. Recursively check if the right subtrees of both trees are similar.
    • d. If all conditions above are met, the trees are considered similar.
  3. If any of the above conditions fail, the trees are not similar.

Let’s apply the algorithm to our previous example:

Step 1:
Check if root values are equal.
5 != 7

Step 2:
Recursively compare left and right subtrees.

Left Subtree of Tree 1:

  • a. Check if root values are equal.
    3 == 4 (Not equal)

Right Subtree of Tree 1:

    8 == 9 (Not equal)

As the root values and the corresponding nodes of the left and right subtrees are not equal, Tree 1 and Tree 2 are not similar.


The concept of similar trees finds applications in various areas of computer science and programming. Some common applications include:

  • Database Management Systems: Similar trees are used in indexing techniques such as B-trees, which enable efficient searching, insertion, and deletion operations.
  • Graph Algorithms: Similar tree structures are utilized in graph algorithms like minimum spanning trees and shortest path algorithms.
  • Data Compression: Similar tree structures can be leveraged for data compression techniques like Huffman coding.


In conclusion, a similar tree refers to two binary trees having the same structure but potentially different node values. Determining similarity between two trees involves comparing their structures using a recursive algorithm. The concept of similar trees finds practical applications in database management systems, graph algorithms, and data compression techniques.

By understanding the concept of similar trees, you can enhance your problem-solving skills when working with data structures and algorithmic challenges.

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