benchmarks/Algorithms/DFS_adjacency_list/problem.md

Depth-First Search on an Adjacency List

Problem Description

Given a directed graph whose vertices are numbered from 0 to vertex_count - 1, perform a depth-first search starting from a valid source vertex. The graph is stored as an array of linked lists: adjacency[u] contains exactly the outgoing neighbors of vertex u.

The graph representation is read-only. The procedure updates the caller-provided visited array so that, when it returns, a vertex is marked if and only if it is reachable from the source vertex.

Input

• adjacency: an array of linked-list heads representing all outgoing adjacency lists.
• vertex_count: the number of vertices.
• visited: an integer array of length vertex_count, initially marking no vertex as visited.
• vertex: the source vertex from which the traversal starts.

Output

The function returns no value. It updates visited in place so that exactly the vertices reachable from vertex are marked as visited. The graph stored in adjacency is unchanged.

Constraints

• 0 < vertex_count < INT_MAX.
• 0 <= vertex < vertex_count.
• Every neighbor appearing in an adjacency list is a valid vertex.
• The graph representation is well formed.
• The initial visited set is empty.

Source

Classical depth-first search problem reconstructed from the verified C artifact.