What Is Sink Node in Data Structure?


Scott Campbell

A sink node, also known as a leaf node or terminal node, is a fundamental concept in data structure. In simple terms, it refers to a node in a tree-like structure that does not have any children. In other words, a sink node is the endpoint of a branch where no further branches or nodes are connected.

Structure of a Sink Node:

A sink node can be visualized as the last stop in a tree-like structure. It is the ultimate destination for any path that originates from the root or any intermediate nodes. Sink nodes do not have any child nodes branching out from them.


Consider a binary tree with various nodes and branches connecting them. In this case, the sink nodes would be the leaf nodes at the bottom-most level of the tree. These leaf nodes do not have any child nodes connected to them and are considered as sink nodes.

Properties of Sink Nodes:

Sink nodes possess certain unique characteristics that differentiate them from other types of nodes in data structures. Some key properties of sink nodes include:

  • A sink node has no outgoing edges or child nodes.
  • A sink node marks the end of a path in a tree-like structure.
  • A sink node does not have any descendants.
  • Sink nodes are often used for representing data elements or storing values in certain applications.

Applications of Sink Nodes:

The concept of sink nodes finds applications in various fields and algorithms. Some notable applications include:

1. Decision Trees:

In decision tree algorithms, where each internal node represents a decision based on specific criteria, the leaf or sink nodes represent the final outcomes or decisions. These outcomes can be classifications such as “Yes” or “No,” predictions, or actions to be taken.

2. Graph Theory:

In graph theory, sink nodes are crucial for determining the properties and behaviors of directed or undirected graphs. Sink nodes can be used to identify the end points of paths or to analyze the overall structure of a graph.

3. Data Storage:

In certain data storage applications, sink nodes are used to represent data elements or values that do not have any further relationships with other data elements. This can be particularly useful in hierarchical or tree-like data structures where leaf nodes act as storage units for specific information.


In summary, a sink node is an essential concept in data structures, representing the endpoint of a branch where no further branches or nodes are connected. Sink nodes possess unique properties and find applications in decision trees, graph theory, and data storage systems.

Understanding the concept of sink nodes is crucial for effectively analyzing and manipulating tree-like structures. By identifying and utilizing sink nodes, developers can optimize algorithms, store data efficiently, and make informed decisions based on the final outcomes represented by these leaf nodes.

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