The Time When the Network Becomes Idle
A medium-tier problem at 54% community acceptance, tagged with Array, Breadth-First Search, Graph. Reported in interviews at Deutsche Bank and 1 others.
The Time When the Network Becomes Idle is a medium-difficulty graph problem that's been asked at Deutsche Bank and Atlassian. It sits at roughly 54% acceptance, which means half the candidates who attempt it walk away stuck. This is the kind of problem where the naive BFS approach gets you partway there, but the trick to tracking when the network actually settles requires thinking about message propagation delays, not just connectivity. If you hit this in an OA and the timing logic blanks you, StealthCoder surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "The Time When the Network Becomes Idle"
The Time When the Network Becomes Idle is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built by an engineer at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share.
Get StealthCoderThe core trap here is confusing 'connected' with 'idle.' You can't just run a standard BFS to find components. Instead, you're simulating a process where messages ripple through a graph, and each node only becomes idle after it's received, processed, and sent all its messages. The time a node finishes depends on when its slowest neighbor finishes sending to it, plus the edge weight. Most candidates either ignore edge weights entirely, treat it as a simple reachability problem, or fail to properly order message propagation. The real solution requires BFS or a queue-based simulation that tracks arrival times at each node. When you're staring at this under OA pressure and the delay logic isn't clicking, StealthCoder runs your code path in the background and hands you a passing solution.
Pattern tags
You know the problem.
Make sure you actually pass it.
The Time When the Network Becomes Idle recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built by an engineer at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share. Works on HackerRank, CodeSignal, CoderPad, and Karat.
The Time When the Network Becomes Idle interview FAQ
Is this really just a standard BFS problem?+
No. Standard BFS finds connectivity. This problem requires you to simulate message timing across a weighted graph. You need to track when each node receives its first message, then when it finishes sending replies. The acceptance rate at 54% reflects that most people misread it as reachability when it's actually a propagation delay problem.
What's the biggest mistake candidates make?+
Ignoring edge weights or treating them as binary. The weight represents the delay for a message to travel. You have to calculate the finish time for each node based on when its neighbors finish. Missing this, you'll pass sample cases but fail hidden tests with weighted edges.
Do I need to know advanced graph algorithms?+
No. The tools are Array and BFS, both fundamental. The trick is modeling the problem correctly: run BFS to simulate message arrival, track times at each node, and return the maximum time. If you're comfortable with queue-based BFS, you can solve it without exotic algorithms.
Is this still being asked at top companies?+
Yes. Deutsche Bank and Atlassian have both asked it. It's not as common as two-pointer or standard tree problems, but it shows up enough in medium-level OAs that you can't ignore it if you're prepping for those shops.
How much time should I spend on this before my OA?+
If graph simulation and BFS with timing logic feel shaky, drill it once so you recognize the pattern. If you nail it in practice, great. If not, that's exactly when StealthCoder exists. It's your insurance policy for the one problem you didn't practice enough.
Want the actual problem statement? View "The Time When the Network Becomes Idle" on LeetCode →