CodingMediumcod-g008

Subject Cycle detectionLevel Mid–Senior~25 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Given a directed graph with n nodes (0..n-1) and a list of directed edges [u, v], determine whether the graph contains at least one directed cycle. Return true if a cycle exists, otherwise false. The graph may be disconnected and may contain self-loops (a self-loop counts as a cycle).

Implement

has_directed_cycle(n: int, edges: list[list[int]]) → bool

Examples

in[4,[[0,1],[1,2],[2,3],[3,1]]]outtrue

What a strong answer looks like

State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.

Learn the concepts

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.