What is the time complexity of the topological sort algorithm?

Algorithm Design Questions Medium



49 Short 51 Medium 39 Long Answer Questions Question Index

What is the time complexity of the topological sort algorithm?

The time complexity of the topological sort algorithm depends on the specific implementation used. However, in general, the most common algorithm for topological sorting, known as the depth-first search (DFS) algorithm, has a time complexity of O(V + E), where V represents the number of vertices (nodes) in the graph and E represents the number of edges.

In the DFS-based topological sort algorithm, we perform a depth-first search on the graph, visiting each vertex and its adjacent vertices. This process takes O(V + E) time as we need to visit each vertex and each edge once. Additionally, we may need to perform additional operations such as maintaining a stack or a queue to store the sorted order, which typically takes O(V) or O(E) time.

It is important to note that this time complexity assumes that the graph is represented using an adjacency list or matrix, which allows for efficient access to the adjacent vertices of each vertex. If the graph is represented using an adjacency matrix, the time complexity can be higher, reaching O(V^2) in the worst case.

Overall, the time complexity of the topological sort algorithm is typically considered to be linear in the number of vertices and edges in the graph, making it an efficient algorithm for sorting directed acyclic graphs.