What Is Depth of a Tree in Data Structure?


Larry Thompson

What Is Depth of a Tree in Data Structure?

In data structure, a tree is a hierarchical data structure that consists of nodes connected by edges. Each node in a tree can have zero or more child nodes, except for the root node which has no parent. The depth of a tree refers to the length of the longest path from the root node to any leaf node in the tree.

Understanding Tree Depth

The depth of a tree is an important metric as it provides information about how balanced or skewed the tree is. A balanced tree has an equal number of nodes on both sides, resulting in a smaller depth. On the other hand, a skewed tree has more nodes on one side compared to the other, leading to a larger depth.

Tree depth is often used as a measure of efficiency in various algorithms that operate on trees. For example, when searching for an element in a binary search tree, the time complexity is directly influenced by the depth of the tree.

Calculating Depth

To calculate the depth of a tree, we can use either recursive or iterative methods.

Recursive Method:

  • Step 1: Start at the root node.
  • Step 2: If the current node is null (i.e., there are no more child nodes), return 0.
  • Step 3: Otherwise, recursively calculate the maximum depth of each child node and return the maximum depth plus one (to account for the current level).

Iterative Method:

  • Step 1: Initialize two variables: current_depth and max_depth, both set to 0.
  • Step 2: Create an empty stack and push the root node onto it.
  • Step 3: Repeat the following steps until the stack is empty:
    • Step 3.1: Pop the top node from the stack.
    • Step 3.2: If the popped node is not null, update current_depth to its depth (current_depth + 1).3: Update max_depth if current_depth is greater than max_depth.4: Push the child nodes of the popped node onto the stack.


Let’s consider a simple binary tree to understand how to calculate its depth using both methods:

       / \
      B   C
     / \
    D   E

In this example, the depth of the tree is equal to 2, as there are two levels from the root node ‘A’ to any leaf node (‘D’ or ‘E’).

In Conclusion

The depth of a tree in data structure refers to the length of the longest path from the root node to any leaf node. It provides insights into how balanced or skewed a tree is and affects various algorithms’ efficiency that operate on trees. Understanding and calculating tree depth using recursive or iterative methods can be useful in optimizing algorithms and analyzing data structures.

You can now confidently explain what tree depth is and how it can be calculated!

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