| 8 | 8 | * @returns {string} |
| 9 | 9 | */ |
| 10 | 10 | export const gamestate = (board) => { |
| 11 | | throw new Error('Remove this line and implement the function'); |
| 11 | // Validate board dimensions |
| 12 | if (board.length !== 3) { |
| 13 | throw new Error('Invalid board: must have 3 rows'); |
| 14 | } |
| 15 | |
| 16 | for (let i = 0; i < 3; i++) { |
| 17 | if (board[i].length !== 3) { |
| 18 | throw new Error('Invalid board: each row must have 3 columns'); |
| 19 | } |
| 20 | } |
| 21 | |
| 22 | // Count Xs and Os |
| 23 | let countX = 0; |
| 24 | let countO = 0; |
| 25 | |
| 26 | for (let i = 0; i < 3; i++) { |
| 27 | for (let j = 0; j < 3; j++) { |
| 28 | const cell = board[i][j]; |
| 29 | if (cell === 'X') { |
| 30 | countX++; |
| 31 | } else if (cell === 'O') { |
| 32 | countO++; |
| 33 | } else if (cell !== ' ') { |
| 34 | throw new Error('Invalid board: contains invalid characters'); |
| 35 | } |
| 36 | } |
| 37 | } |
| 38 | |
| 39 | // Check for wins |
| 40 | const checkWin = (player) => { |
| 41 | // Check rows |
| 42 | for (let i = 0; i < 3; i++) { |
| 43 | if (board[i][0] === player && board[i][1] === player && board[i][2] === player) { |
| 44 | return true; |
| 45 | } |
| 46 | } |
| 47 | |
| 48 | // Check columns |
| 49 | for (let j = 0; j < 3; j++) { |
| 50 | if (board[0][j] === player && board[1][j] === player && board[2][j] === player) { |
| 51 | return true; |
| 52 | } |
| 53 | } |
| 54 | |
| 55 | // Check diagonals |
| 56 | if (board[0][0] === player && board[1][1] === player && board[2][2] === player) { |
| 57 | return true; |
| 58 | } |
| 59 | |
| 60 | if (board[0][2] === player && board[1][1] === player && board[2][0] === player) { |
| 61 | return true; |
| 62 | } |
| 63 | |
| 64 | return false; |
| 65 | }; |
| 66 | |
| 67 | const xWins = checkWin('X'); |
| 68 | const oWins = checkWin('O'); |
| 69 | |
| 70 | // Edge Case: Both players win (impossible) |
| 71 | if (xWins && oWins) { |
| 72 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 73 | } |
| 74 | |
| 75 | // For boards with wins, check for impossible scenarios and excessive turn count violations |
| 76 | if (xWins || oWins) { |
| 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 | // Check for excessively wrong turn counts |
| 83 | // X cannot have more than 2 more moves than O |
| 84 | if (countX > countO + 2) { |
| 85 | throw new Error('Wrong turn order: X went twice'); |
| 86 | } |
| 87 | |
| 88 | // O cannot have more than 2 more moves than X |
| 89 | if (countO > countX + 2) { |
| 90 | throw new Error('Wrong turn order: O went twice'); |
| 91 | } |
| 92 | |
| 93 | // Check if game continued after win by checking if opponent has a complete line |
| 94 | // If X wins, check if O has a complete line (indicating O continued playing after X won) |
| 95 | if (xWins) { |
| 96 | // Check if O has a complete line |
| 97 | for (let i = 0; i < 3; i++) { |
| 98 | if (board[i][0] === 'O' && board[i][1] === 'O' && board[i][2] === 'O') { |
| 99 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 100 | } |
| 101 | } |
| 102 | |
| 103 | for (let j = 0; j < 3; j++) { |
| 104 | if (board[0][j] === 'O' && board[1][j] === 'O' && board[2][j] === 'O') { |
| 105 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 106 | } |
| 107 | } |
| 108 | |
| 109 | if (board[0][0] === 'O' && board[1][1] === 'O' && board[2][2] === 'O') { |
| 110 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 111 | } |
| 112 | |
| 113 | if (board[0][2] === 'O' && board[1][1] === 'O' && board[2][0] === 'O') { |
| 114 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 115 | } |
| 116 | } |
| 117 | |
| 118 | // If O wins, check if X has a complete line (indicating X continued playing after O won) |
| 119 | if (oWins) { |
| 120 | // Check if X has a complete line |
| 121 | for (let i = 0; i < 3; i++) { |
| 122 | if (board[i][0] === 'X' && board[i][1] === 'X' && board[i][2] === 'X') { |
| 123 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 124 | } |
| 125 | } |
| 126 | |
| 127 | for (let j = 0; j < 3; j++) { |
| 128 | if (board[0][j] === 'X' && board[1][j] === 'X' && board[2][j] === 'X') { |
| 129 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 130 | } |
| 131 | } |
| 132 | |
| 133 | if (board[0][0] === 'X' && board[1][1] === 'X' && board[2][2] === 'X') { |
| 134 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 135 | } |
| 136 | |
| 137 | if (board[0][2] === 'X' && board[1][1] === 'X' && board[2][0] === 'X') { |
| 138 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 139 | } |
| 140 | } |
| 141 | } else { |
| 142 | // No win - validate normal turn order |
| 143 | // O cannot start the game (special case when X has 0 moves) |
| 144 | if (countX === 0 && countO > 0) { |
| 145 | throw new Error('Wrong turn order: O started'); |
| 146 | } |
| 147 | |
| 148 | // X cannot have more than one move more than O |
| 149 | if (countX > countO + 1) { |
| 150 | throw new Error('Wrong turn order: X went twice'); |
| 151 | } |
| 152 | |
| 153 | // O cannot have more moves than X |
| 154 | if (countO > countX) { |
| 155 | throw new Error('Wrong turn order: O went twice'); |
| 156 | } |
| 157 | } |
| 158 | |
| 159 | // Now validate win consistency |
| 160 | if (xWins || oWins) { |
| 161 | // Edge Case: Both players win (impossible) |
| 162 | if (xWins && oWins) { |
| 163 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 164 | } |
| 165 | |
| 166 | // Check if game continued after win by checking if opponent has a complete line |
| 167 | // If X wins, check if O has a complete line (indicating O continued playing after X won) |
| 168 | if (xWins) { |
| 169 | const oHasCompleteLine = checkWin('O'); |
| 170 | if (oHasCompleteLine) { |
| 171 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 172 | } |
| 173 | } |
| 174 | |
| 175 | // If O wins, check if X has a complete line (indicating X continued playing after O won) |
| 176 | if (oWins) { |
| 177 | const xHasCompleteLine = checkWin('X'); |
| 178 | if (xHasCompleteLine) { |
| 179 | throw new Error('Impossible board: game should have ended after the game was won'); |
| 180 | } |
| 181 | } |
| 182 | } |
| 183 | |
| 184 | // Determine game state |
| 185 | if (xWins || oWins) { |
| 186 | return 'win'; |
| 187 | } |
| 188 | |
| 189 | // Edge Case: Board is full (draw) |
| 190 | if (countX + countO === 9) { |
| 191 | return 'draw'; |
| 192 | } |
| 193 | |
| 194 | // Edge Case: Game is ongoing |
| 195 | return 'ongoing'; |
| 12 | 196 | }; |
| 197 | |
| 198 | // Handled Edge Cases: |
| 199 | // 1. Invalid board dimensions |
| 200 | // 2. Invalid characters on board |
| 201 | // 3. Wrong turn order - O started |
| 202 | // 4. Wrong turn order - X went twice in a row |
| 203 | // 5. Both players win (impossible) |
| 204 | // 6. Game continued after X win |
| 205 | // 7. Game continued after O win |
| 206 | // 8. Board is full (draw) |
| 207 | // 9. Game is ongoing |