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In this approach, we use a 3x3 board to simulate the mechanics of a Tic Tac Toe game. For every move made, we place the respective player's symbol ('X' for player A and 'O' for player B) on the board. After each move, we check if this move results in a win for any player by verifying if there are three matching symbols in any row, column, or diagonal. If a win is found, that player is declared the winner and the game ends. If all moves are exhausted without a winner, the game is declared a draw. If there are remaining moves, the game is pending.
Time Complexity: O(n), where n is the length of the moves. In the worst case, it checks 8 winning conditions for all 9 moves.
Space Complexity: O(1), since the board is of fixed size (3x3).
1function tictactoe(moves) {
2 const board = Array.from({length: 3}, () => Array(3).fill(' '));
3 let player = 'X';
4 for (const [x, y] of moves) {
5 board[x][y] = player;
6 player = player === 'X' ? 'O' : 'X';
7 }
8
9 for (let i = 0; i < 3; i++) {
10 if (board[i][0] !== ' ' && board[i][0] === board[i][1] && board[i][1] === board[i][2])
11 return board[i][0] === 'X' ? "A" : "B";
12 if (board[0][i] !== ' ' && board[0][i] === board[1][i] && board[1][i] === board[2][i])
13 return board[0][i] === 'X' ? "A" : "B";
14 }
15 if (board[0][0] !== ' ' && board[0][0] === board[1][1] && board[1][1] === board[2][2])
16 return board[0][0] === 'X' ? "A" : "B";
17 if (board[0][2] !== ' ' && board[0][2] === board[1][1] && board[1][1] === board[2][0])
18 return board[0][2] === 'X' ? "A" : "B";
19 return moves.length === 9 ? "Draw" : "Pending";
20}
21
22// Example usage
23console.log(tictactoe([[0,0],[2,0],[1,1],[2,1],[2,2]]));
24This JavaScript function follows the simulation approach where we first create a 3x3 board. Each move is performed by the current player who alternates between 'X' and 'O'. After applying all the moves, the winning condition is checked for rows, columns, and diagonals, updating the outcome accordingly.
Instead of simulating the grid itself, this approach tracks the status of each row, column, and the two diagonals using counters. Each player will have their counters, incrementing or decrementing upon making a move. The first instance a counter reaches 3 or -3 indicates a player has won the game. This method significantly reduces the need to check the grid extensively for each move while still adhering to the rules of Tic Tac Toe.
Time Complexity: O(n), where n is the number of moves.
Space Complexity: O(1), as only fixed-size counters are involved.
This solution uses integer counters to track the influence of moves on the board. Each player's move updates these counters; the goal is to detect a completion of three moves in any direction (horizontally, vertically, or diagonally). This approach efficiently determines the winner without maintaining the entire board's state.