CodingHardcod-p006

Subject GraphsLevel Senior–Staff~35 minCommon in Algorithms & data structures interviewsIndustries Software development, Technology

Question

You are given a directed network of n nodes (labelled 1..n) and a list of travel times [u, v, w] meaning a signal from u reaches v after w time. A signal starts at node k. Return the time for all nodes to receive it, or -1 if some node is unreachable.

Implement

network_delay_time(times: list[list[int]], n: int, k: int) → int

Examples

in[[[2,1,1],[2,3,1],[3,4,1]],4,2]out2

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.