Xai·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say

May 2026

Summary

Xai software engineer interview that was basically a full backend implementation exercise. They had me design a checkers game from scratch, which sounds simple enough until you're actually in it trying to remember how capture chains work under pressure.

Questions Asked (1)

Design and implement the backend for a checkers game, covering board setup, move validation, capture logic (jumping over opponent pieces), and win condition detection.

System DesignAlgorithms & Data StructuresTechnical Trade-offs

Author's notes

I started with board initialization since that felt safe, a 2D grid with piece positions.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and constraints (board size, rules, API vs. library, performance needs), then outline a clean object-oriented design with clear separation of concerns (Board, Piece, MoveValidator, GameEngine). Walk through the core algorithms for move generation, capture chains, and win detection, discussing trade-offs and edge cases.

Pro tip: Emphasize testability and extensibility: propose a design where rules are pluggable and the board state is immutable, making it easy to unit test and support variants like international draughts.

1. Clarify Requirements and Scope

Ask about board size (8x8), rule variants (American/English checkers), API expectations (REST, library), and performance constraints. Confirm whether to handle multi-jump chains and king promotion.

2. Design Data Model and Board Representation

Propose a Board class with a 2D array or bitboard, Piece objects with color and king status, and a Move class. Discuss trade-offs between simplicity and performance.

3. Implement Move Validation and Capture Logic

Detail algorithms for generating legal moves: diagonal moves for men, any direction for kings, mandatory captures, and recursive multi-jump resolution. Handle edge cases like blocked paths and promotion during capture.

4. Detect Win Conditions and Game State

Explain how to check for no legal moves or no pieces left for a player, and how to track turns. Consider draw conditions (e.g., repetition) if relevant.

5. Discuss Trade-offs, Testing, and Extensibility

Compare design choices (e.g., bitboard vs. array), outline unit test cases for move validation and captures, and suggest how to extend to variants or add AI.

Key Points to Mention

Board representation: 2D array vs. bitboard, and performance implications
Move generation: directional moves, mandatory captures, and multi-jump recursion
Capture logic: jumping over opponent pieces, removal, and promotion during capture
Win condition: no legal moves or no pieces remaining, and turn management
Edge cases: king promotion, blocked captures, and stalemate/draw scenarios
Testing strategy: unit tests for move validation, capture chains, and win detection

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