Meta·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say

Apr 2026

Summary

Meta software engineer interview with a coding question involving bomb blast mechanics in a grid. I leaned pretty hard on AI to get through it, which made the whole thing feel like a weird performance where I was just narrating code I barely wrote.

Questions Asked (1)

Given a grid, simulate a bomb that destroys cells in a cross pattern (up, down, left, right from the detonation point). Implement the logic to handle this.

Algorithms & Data Structures

Author's notes

I fed this straight to an AI and just read through what came back.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Clarify the problem constraints (grid size, bomb radius, multiple bombs, obstacles) and then propose a solution that simulates the bomb's effect by iterating over affected cells. Optimize by considering time and space complexity, and discuss trade-offs between different approaches.

Pro tip: Demonstrate awareness of edge cases (e.g., bombs at borders, overlapping bombs) and discuss how to handle them efficiently. Mention that in a real system, you might use a difference array or 2D prefix sums to optimize multiple bomb detonations.

1. Clarify Requirements

Ask questions to understand the grid dimensions, bomb radius, whether there are obstacles, and if multiple bombs are detonated simultaneously or sequentially.

2. Define the Simulation

Explain how to mark cells destroyed by a bomb: for a given center (r, c) and radius k, destroy all cells (r±i, c) and (r, c±i) for i from 0 to k, within grid bounds.

3. Choose Data Structures

Use a 2D boolean array or a set to track destroyed cells. For multiple bombs, consider using a difference array for O(1) range updates per row/column.

4. Analyze Complexity

Discuss time complexity: naive simulation is O(B * k) where B is number of bombs; optimized with difference arrays can be O(R*C + B). Space complexity is O(R*C).

5. Handle Edge Cases

Address bombs near edges, overlapping destruction, and ensure no out-of-bounds access. Test with small grids and multiple bombs.

Key Points to Mention

Grid representation (2D array) and boundary checks.
Bomb effect: cross pattern with radius k (Manhattan distance ≤ k).
Time complexity of naive vs optimized approaches.
Using difference arrays or 2D prefix sums for multiple bombs.
Handling overlapping bombs and ensuring cells are marked once.
Edge cases: bombs at corners, large radius, empty grid.

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