| 1 | | // |
| 2 | | // This is only a SKELETON file for the 'State of Tic Tac Toe' exercise. It's been provided as a |
| 3 | | // convenience to get you started writing code faster. |
| 4 | | // |
| 5 | | |
| 6 | | /** |
| 7 | | * @param {string[]} board |
| 8 | | * @returns {string} |
| 1 | /* |
| 2 | * Determines the state of a Tic-Tac-Toe game based on the given board. |
| 3 | * |
| 4 | * @param {string[]} board - An array of strings representing the 3x3 game board. |
| 5 | * Each string represents a row with characters 'X', 'O', or ' '. |
| 6 | * @returns {string} - Returns 'win', 'draw', or 'ongoing' based on the game state. |
| 7 | * @throws {Error} - Throws an error for invalid board states with specific messages. |
| 9 | 8 | */ |
| 10 | 9 | export const gamestate = (board) => { |
| 11 | | throw new Error('Remove this line and implement the function'); |
| 12 | | }; |
| 10 | // Validate board structure |
| 11 | if (!board || board.length !== 3) { |
| 12 | throw new Error('Invalid board: must have exactly 3 rows'); |
| 13 | } |
| 14 | |
| 15 | for (let i = 0; i < 3; i++) { |
| 16 | if (!board[i] || board[i].length !== 3) { |
| 17 | throw new Error('Invalid board: each row must have exactly 3 columns'); |
| 18 | } |
| 19 | } |
| 20 | |
| 21 | // Count X's and O's |
| 22 | let countX = 0; |
| 23 | let countO = 0; |
| 24 | |
| 25 | for (let i = 0; i < 3; i++) { |
| 26 | for (let j = 0; j < 3; j++) { |
| 27 | const cell = board[i][j]; |
| 28 | if (cell === 'X') { |
| 29 | countX++; |
| 30 | } else if (cell === 'O') { |
| 31 | countO++; |
| 32 | } else if (cell !== ' ') { |
| 33 | throw new Error('Invalid board: contains invalid characters'); |
| 34 | } |
| 35 | } |
| 36 | } |
| 37 | |
| 38 | // Edge Case: Invalid turn order - X went twice in a row |
| 39 | if (countX > countO + 1) { |
| 40 | throw new Error('Wrong turn order: X went twice'); |
| 41 | } |
| 42 | |
| 43 | // Edge Case: Invalid turn order - O went twice in a row |
| 44 | if (countO > countX) { |
| 45 | throw new Error('Wrong turn order: O went twice'); |
| 46 | } |
| 47 | |
| 48 | // Check for wins |
| 49 | const checkWin = (player) => { |
| 50 | // Check rows |
| 51 | for (let i = 0; i < 3; i++) { |
| 52 | if (board[i][0] === player && board[i][1] === player && board[i][2] === player) { |
| 53 | return true; |
| 54 | } |
| 55 | } |
| 56 | |
| 57 | // Check columns |
| 58 | for (let j = 0; j < 3; j++) { |
| 59 | if (board[0][j] === player && board[1][j] === player && board[2][j] === player) { |
| 60 | return true; |
| 61 | } |
| 62 | } |
| 63 | |
| 64 | // Check diagonals |
| 65 | if (board[0][0] === player && board[1][1] === player && board[2][2] === player) { |
| 66 | return true; |
| 67 | } |
| 68 | |
| 69 | if (board[0][2] === player && board[1][1] === player && board[2][0] === player) { |
| 70 | return true; |
| 71 | } |
| 72 | |
| 73 | return false; |
| 74 | }; |
| 75 | |
| 76 | const xWins = checkWin('X'); |
| 77 | const oWins = checkWin('O'); |
| 78 | |
| 79 | // Edge Case: Both players win (impossible in a valid game) |
| 80 | if (xWins && oWins) { |
| 81 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 82 | } |
| 83 | |
| 84 | // Edge Case: X wins but O made another move |
| 85 | if (xWins && countX === countO) { |
| 86 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 87 | } |
| 88 | |
| 89 | // Edge Case: O wins but X made another move |
| 90 | if (oWins && countX > countO) { |
| 91 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 92 | } |
| 93 | |
| 94 | // Determine game state |
| 95 | if (xWins || oWins) { |
| 96 | return 'win'; |
| 97 | } |
| 98 | |
| 99 | // Edge Case: Board is full with no winner (draw) |
| 100 | if (countX + countO === 9) { |
| 101 | return 'draw'; |
| 102 | } |
| 103 | |
| 104 | // Edge Case: Game is not finished yet (ongoing) |
| 105 | return 'ongoing'; |
| 106 | |
| 107 | // Handled Edge Cases: |
| 108 | // - Invalid board dimensions |
| 109 | // - Invalid characters on board |
| 110 | // - O starting the game |
| 111 | // - X going twice in a row |
| 112 | // - Both players winning |
| 113 | // - Continuing play after X wins |
| 114 | // - Continuing play after O wins |
| 115 | // - Full board with no winner (draw) |
| 116 | // - Game not finished yet (ongoing) |
| 117 | }; |