Code RoomDirected cycle detection
MediumPrep Room Coding #68

Directed cycle detection

CodingAlgorithms & data structuresMid–Senior~25 min

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.

0:00 of about 25 min
InputExpectedGot
[4,[[0,1],[1,2],[2,3],[3,1]]]truenot run yetsample