Tic-Tac-Toe Game Logic With a Random-Move Computer Player

Implement the logic of a tic-tac-toe game. The focus is the game logic, not a user interface. Two players, X and O, take turns placing their mark on an empty cell of the board; the first player to fill a whole row, column or diagonal with their mark wins, and a full board with no winner is a draw. Late in the round a second part was added: let the computer play one side, choosing its moves at random. ### Clarifying Questions - Is the board always 3 × 3, or should it support an n × n board where a full row, column or diagonal wins? - Who moves first, and is the human always X? - How should an invalid move be reported: an exception, an error value, or a prompt to try again? - Is the game driven by a console loop, or by method calls from tests or another program? ### Part 1 — Game logic Write the game state and the operations two players need: make a move, reject invalid moves, detect a win or a draw after each move, and report whose turn it is and whether the game is over. ```hint Only the last move can finish a line A move can only complete a line that passes through the cell just played. Think about how to test that without rescanning the whole board. ``` #### What This Part Should Cover - A clear state model: the board, the player to move, and the game status - Validation of every move: bounds, occupied cells, and moves after the game has ended - Correct win and draw detection, and its cost per move ### Part 2 — Random computer player Add a computer player that chooses uniformly at random among the empty cells, and run a game between a human and the computer, or between two computer players. ```hint Keep the randomness injectable Decide how a test can make the computer's moves predictable without changing the game code. ``` #### What This Part Should Cover - A uniform choice among legal moves only - A player abstraction that lets human and computer players share one game loop - Deterministic tests through a seeded or injected random source ### What a Strong Answer Covers - Settles board size, turn order and error handling before coding - Separates the rules and state from input and output and from player strategy - Validates every move and ends the game cleanly on a win or a draw - Tests for wins on rows, columns and both diagonals, for draws, and for invalid moves - Talks through the code while writing it and names improvements beyond the minimum, such as a stronger computer player ### Follow-up Questions - Generalize to an n × n board where k marks in a row win. What changes in win detection? - Make the computer take a winning move when it has one and block the opponent's immediate win otherwise. How do you add this without touching the game rules? - How would you make the computer never lose on a 3 × 3 board, and what does that cost? - How would you add undo?