← Uber Interview Insights

Uber·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say
Apr 2026

Summary

Uber SWE interview with a grid-based robot localization problem. The core challenge wasn't the algorithm itself but keeping coordinate conventions straight under pressure, which tripped me up more than I expected.

Questions Asked (1)

Q1

A robot is placed somewhere on an m x n grid. You're given the robot's distance to the nearest wall or obstacle in each of the four cardinal directions. Find the robot's coordinates.

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

Started with brute force, checking every cell and seeing if the four distances matched.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Clarify the problem constraints and assumptions, then derive the robot's coordinates by reasoning about how the given distances constrain its position relative to walls or obstacles. Consider edge cases and validate your solution with examples.

Pro tip: Demonstrate systematic problem-solving by explicitly stating assumptions and walking through a concrete example before generalizing. This shows clarity and reduces ambiguity.

1. Clarify the problem

Ask questions to confirm the grid dimensions, whether walls/obstacles are known, and if distances are exact or approximate. Ensure you understand what 'distance to nearest wall or obstacle' means in each direction.

2. Define coordinate system

Establish a coordinate system (e.g., top-left as (0,0)) and define how distances map to coordinates. For example, if the robot is at (r, c), the distance to the left wall is c, to the right wall is n-1-c, etc.

3. Derive equations

Use the given distances to set up equations. For instance, left distance = c, right distance = n-1-c, top distance = r, bottom distance = m-1-r. Solve for r and c.

4. Handle obstacles and edge cases

If obstacles are present, the distances may not directly give coordinates. Discuss how to handle such cases, possibly by using the distances to narrow down possible positions or by assuming obstacles are walls.

5. Validate and test

Test your solution with simple examples (e.g., 1x1 grid, robot at corner) and edge cases (e.g., distances that imply no solution). Discuss time and space complexity.

Key Points to Mention

  • Coordinate system and mapping distances to indices
  • Equations for distances to walls in each direction
  • Handling obstacles vs. walls
  • Edge cases: robot at corner, no solution, multiple solutions
  • Time and space complexity (O(1) if direct calculation)
  • Clarifying questions to resolve ambiguity

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