Tic Tac Toe III
Problem statement
Tic Tac Toe III is the complete minimax AI implementation. Instead of a two-player game, the player faces a computer opponent that plays perfectly — it never loses. This tests your ability to implement the minimax algorithm in a React component and integrate it with the game state from previous parts.
Build on the Tic Tac Toe game engine to add a CPU player that uses minimax to find the optimal move. After the human plays, the CPU immediately calculates and plays its best response. The CPU should be unbeatable — the best outcome a human can achieve is a draw.
The algorithmic challenge is the minimax function: recursively evaluate all possible future game states, assign scores (+10 for CPU win, -10 for human win, 0 for draw), and pick the move with the highest score. Alpha-beta pruning is bonus credit.
Requirements & constraints
- CPU uses minimax to play optimally — never loses
- CPU plays automatically after human move
- Game correctly detects win, draw, and ongoing states
- Visual indicator shows CPU is thinking (even if instant)
- Human is always X (first), CPU is always O
- Restart button resets the game
How to approach Tic Tac Toe III
The strategy an interviewer expects you to reach for.
Why This Question Exists Tic Tac Toe III — the minimax AI — is one of the classic algorithm questions adapted for a UI context. It tests whether you can implement a recursive search algorithm, correctly model the game as a tree of states, and integrate the AI into React's state model cleanly. Candidates who know the algorithm but can't wire it to React's event loop fail this question.
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