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Disney·Machine Learning Engineer·Technical Phone Screen·Senior

SeniorPrefer not to say
Jun 2026

Summary

Disney ML engineer interview that turned out to have nothing to do with ML. The one question was a geometry/graph logic puzzle dressed up as a coding problem, which I did not see coming.

Questions Asked (1)

Q1

Several points move through 2D space, each chasing a designated target point according to a directed graph structure (cycles and chains both possible). Will all points eventually converge to a single location? If so, when? If not, describe what happens long-term.

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

The recruiter called it an ML coding round so I showed up mentally prepped to talk about model training pipelines or loss functions or something.

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AI HintsAI Generated

Suggested Approach

Model the system as a directed graph where each node moves toward its target at a constant speed. Analyze the long-term behavior by identifying cycles and chains, then determine convergence based on whether the graph has a single sink or multiple sinks. Use mathematical reasoning to show that points in cycles converge to the cycle's centroid, while chains converge to the sink.

Pro tip: Relate the problem to real-world applications like particle systems in animation or distributed consensus, showing you can connect theory to practice. Mention that the convergence time depends on the initial distances and speeds, and discuss edge cases like multiple cycles or disconnected components.

1. Graph Representation

Represent the points and their targets as a directed graph, where each node has exactly one outgoing edge (its target). Identify cycles and chains (trees leading into cycles).

2. Convergence of Cycles

For a cycle of points, show that they move toward each other and eventually meet at the centroid of the cycle. Use symmetry or linear algebra to prove convergence.

3. Convergence of Chains

For chains (nodes not in cycles), they eventually enter a cycle or a sink. If the graph has a single sink (a node with no outgoing edge), all points converge to that sink. If multiple sinks, points converge to their respective sinks.

4. Long-term Behavior

Determine if all points converge to a single location: this happens only if the graph has a single sink (which could be a cycle or a fixed point). Otherwise, points converge to multiple locations (one per sink).

5. Convergence Time

Discuss that convergence time depends on the initial distances and speeds. In continuous time, convergence is asymptotic; in discrete steps, it may be finite if points meet exactly.

Key Points to Mention

  • Directed graph with out-degree 1, so each component has exactly one cycle.
  • Cycles converge to their centroid; chains converge to the cycle they feed into.
  • If there is a single sink (cycle or fixed point), all points converge to one location.
  • If multiple sinks, points converge to multiple locations, not a single one.
  • Convergence time depends on initial distances and speeds; in continuous time, it's asymptotic.
  • Edge cases: self-loops (fixed points), two-node cycles, disconnected components.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.