| 8 | 8 | * @returns {string} |
| 9 | 9 | */ |
| 10 | 10 | export const gamestate = (board) => { |
| 11 | | throw new Error('Remove this line and implement the function'); |
| 11 | // Edge Case: Board is not 3x3 |
| 12 | if (board.length !== 3 || board.some(row => row.length !== 3)) { |
| 13 | throw new Error('Invalid board: must be 3x3'); |
| 14 | } |
| 15 | |
| 16 | // Count X's and O's and check for invalid characters |
| 17 | let xCount = 0; |
| 18 | let oCount = 0; |
| 19 | let hasInvalidChar = false; |
| 20 | |
| 21 | for (let i = 0; i < 3; i++) { |
| 22 | for (let j = 0; j < 3; j++) { |
| 23 | const cell = board[i][j]; |
| 24 | if (cell !== 'X' && cell !== 'O' && cell !== ' ') { |
| 25 | hasInvalidChar = true; |
| 26 | } |
| 27 | if (cell === 'X') xCount++; |
| 28 | if (cell === 'O') oCount++; |
| 29 | } |
| 30 | } |
| 31 | |
| 32 | // Check for wins |
| 33 | const checkWin = (player) => { |
| 34 | // Check rows |
| 35 | for (let i = 0; i < 3; i++) { |
| 36 | if (board[i][0] === player && board[i][1] === player && board[i][2] === player) { |
| 37 | return true; |
| 38 | } |
| 39 | } |
| 40 | |
| 41 | // Check columns |
| 42 | for (let j = 0; j < 3; j++) { |
| 43 | if (board[0][j] === player && board[1][j] === player && board[2][j] === player) { |
| 44 | return true; |
| 45 | } |
| 46 | } |
| 47 | |
| 48 | // Check diagonals |
| 49 | if (board[0][0] === player && board[1][1] === player && board[2][2] === player) { |
| 50 | return true; |
| 51 | } |
| 52 | if (board[0][2] === player && board[1][1] === player && board[2][0] === player) { |
| 53 | return true; |
| 54 | } |
| 55 | |
| 56 | return false; |
| 57 | }; |
| 58 | |
| 59 | // Debug win detection for specific case |
| 60 | // For board ['XOX', ' O ', ' XO']: |
| 61 | // board[0] = 'XOX', board[1] = ' O ', board[2] = ' XO' |
| 62 | // Column 1: board[0][1] = 'O', board[1][1] = 'O', board[2][1] = 'O' - should be win! |
| 63 | |
| 64 | // Debug: Check win detection for 'O' with board ['XOX', ' O ', ' XO'] |
| 65 | // Row 0: XOX - no |
| 66 | // Row 1: ' O ' - no |
| 67 | // Row 2: ' XO' - no |
| 68 | // Col 0: X X - no |
| 69 | // Col 1: O O - yes! This should return true |
| 70 | // Col 2: X O - no |
| 71 | // Diag 1: X X - no |
| 72 | // Diag 2: X X - no |
| 73 | |
| 74 | const xWins = checkWin('X'); |
| 75 | const oWins = checkWin('O'); |
| 76 | |
| 77 | // Edge Case: Both players win (impossible) |
| 78 | if (xWins && oWins) { |
| 79 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 80 | } |
| 81 | |
| 82 | // Edge Case: Game continued after win |
| 83 | if (xWins && xCount === oCount) { |
| 84 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 85 | } |
| 86 | |
| 87 | // Edge Case: Game continued after win |
| 88 | if (oWins && xCount > oCount) { |
| 89 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 90 | } |
| 91 | |
| 92 | // Edge Case: Wrong turn order - validate based on win state |
| 93 | if (xWins) { |
| 94 | // X won, so X should have exactly one more piece than O |
| 95 | if (xCount < oCount) { |
| 96 | throw new Error('Wrong turn order: O started'); |
| 97 | } |
| 98 | if (xCount > oCount + 1) { |
| 99 | throw new Error('Wrong turn order: X went twice'); |
| 100 | } |
| 101 | } else if (oWins) { |
| 102 | // O won, so counts should be equal |
| 103 | if (oCount < xCount) { |
| 104 | throw new Error('Wrong turn order: X went twice'); |
| 105 | } |
| 106 | if (oCount > xCount) { |
| 107 | throw new Error('Wrong turn order: O went twice'); |
| 108 | } |
| 109 | } else { |
| 110 | // No one has won yet, check normal turn order |
| 111 | // O started |
| 112 | if (oCount > 0 && xCount === 0) { |
| 113 | throw new Error('Wrong turn order: O started'); |
| 114 | } |
| 115 | |
| 116 | // X went twice |
| 117 | if (xCount > oCount + 1) { |
| 118 | throw new Error('Wrong turn order: X went twice'); |
| 119 | } |
| 120 | |
| 121 | // O went twice |
| 122 | if (oCount > xCount + 1) { |
| 123 | throw new Error('Wrong turn order: O went twice'); |
| 124 | } |
| 125 | } |
| 126 | |
| 127 | // Edge Case: Invalid characters on board (check after turn order as per test comment) |
| 128 | if (hasInvalidChar) { |
| 129 | throw new Error('Invalid board: contains invalid characters'); |
| 130 | } |
| 131 | |
| 132 | // Determine game state |
| 133 | if (xWins) { |
| 134 | return 'win'; |
| 135 | } |
| 136 | |
| 137 | if (oWins) { |
| 138 | return 'win'; |
| 139 | } |
| 140 | |
| 141 | // If board is full, it's a draw |
| 142 | if (xCount + oCount === 9) { |
| 143 | return 'draw'; |
| 144 | } |
| 145 | |
| 146 | // Otherwise, game is ongoing |
| 147 | return 'ongoing'; |
| 12 | 148 | }; |
| 149 | |
| 150 | // Handled Edge Cases: Board is not 3x3, Invalid characters on board, Wrong turn order - O started, Wrong turn order - X went twice, Both players win (impossible), Game continued after win |