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dark alpha capital·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say
Jun 2026

Summary

Interviewed for a software engineer role at Dark Alpha Capital and got hit with an assignment optimization problem. Pretty algorithmic heavy, felt like a competitive programming round more than a typical SWE screen.

Questions Asked (1)

Q1

You have n analysts and m field devices placed on a 2D grid. Each analyst must be assigned exactly one distinct device, and the cost of each assignment is the Manhattan distance between them. Find the minimum total assignment cost. Constraints: n up to 10, m up to 15.

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

My first instinct was greedy and it was wrong.

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AI HintsAI Generated

Suggested Approach

Model the problem as a minimum cost bipartite matching between analysts and devices, where edge weights are Manhattan distances. Since n ≤ 10 and m ≤ 15, use dynamic programming with bitmask over devices to compute the minimum cost assignment efficiently.

Pro tip: Mention that the DP state can be optimized by only considering the first n devices or using memoization, and discuss the trade-off between DP and Hungarian algorithm given the small constraints.

1. Clarify the problem

Restate the problem: assign each of n analysts to a distinct device to minimize total Manhattan distance. Confirm constraints and that n ≤ m.

2. Choose an algorithm

Select dynamic programming with bitmask over devices (or Hungarian algorithm) due to small n and m. Explain why DP is suitable: state space 2^m * n is manageable.

3. Define DP state and transition

Define dp[i][mask] as min cost to assign first i analysts using devices in mask. Transition: dp[i][mask] = min over j not in mask of dp[i-1][mask without j] + dist(i-1, j).

4. Implement and optimize

Implement iteratively or recursively with memoization. Optimize by precomputing distances and using bit operations. Discuss time complexity O(n * 2^m * m).

5. Test and analyze

Test with small cases, edge cases (n=0, n=m). Analyze complexity and compare with alternative approaches like Hungarian algorithm O(n^2 m).

Key Points to Mention

  • Manhattan distance calculation: |x1 - x2| + |y1 - y2|
  • Bipartite matching formulation
  • Dynamic programming with bitmask (state compression)
  • Time and space complexity analysis
  • Alternative: Hungarian algorithm for assignment problem
  • Handling constraints: n ≤ 10, m ≤ 15

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