feat: add console-based Tic-Tac-Toe game in puzzles and games package

Author: Mishu03

src/main/java/com/thealgorithms/puzzlesandgames/TicTacToe.java

@@ -0,0 +1,112 @@
+package com.thealgorithms.puzzlesandgames;
+
+import java.util.Scanner;
+
+/**
+ * The {@code TicTacToe} class provides a console-based 2-player Tic-Tac-Toe game.
+ * Players take turns marking a 3x3 grid until one wins or the game ends in a tie.
+ *
+ * <p>
+ * This implementation demonstrates basic programming concepts in Java:
+ * 1. 2D arrays for the game board
+ * 2. Loops and conditionals for game logic
+ * 3. Input handling with {@link Scanner}
+ * </p>
+ *
+ * <p>
+ * The {@code play} method runs the game loop, {@code printBoard} displays
+ * the board, and {@code checkWin} determines if a player has won.
+ * </p>
+ *
+ * <p>
+ * Time Complexity: O(1) for each move (constant operations per turn)  
+ * Space Complexity: O(1) additional space besides the board
+ * </p>
+ */
+public final class TicTacToe {
+
+    private static final char[][] board = {{'1','2','3'}, {'4','5','6'}, {'7','8','9'}};
+
+    private TicTacToe() {
+        // Prevent instantiation
+    }
+
+    /**
+     * Main entry point to start the Tic-Tac-Toe game.
+     *
+     * @param args command-line arguments (not used)
+     */
+    public static void main(String[] args) {
+        play();
+    }
+
+    /**
+     * Runs the main game loop for two players.
+     */
+    public static void play() {
+        Scanner scanner = new Scanner(System.in);
+        char currentPlayer = 'X';
+        int moves = 0;
+        boolean won = false;
+
+        System.out.println("Welcome to Tic-Tac-Toe!");
+
+        while (moves < 9 && !won) {
+            printBoard();
+            System.out.print("Player " + currentPlayer + ", enter a position (1-9): ");
+            int pos = scanner.nextInt();
+            int row = (pos - 1) / 3;
+            int col = (pos - 1) % 3;
+
+            if (board[row][col] != 'X' && board[row][col] != 'O') {
+                board[row][col] = currentPlayer;
+                moves++;
+                won = checkWin(currentPlayer);
+                if (!won) {
+                    currentPlayer = (currentPlayer == 'X') ? 'O' : 'X';
+                }
+            } else {
+                System.out.println("Position already taken. Try again.");
+            }
+        }
+
+        printBoard();
+        if (won) {
+            System.out.println("Player " + currentPlayer + " wins!");
+        } else {
+            System.out.println("It's a tie!");
+        }
+
+        scanner.close();
+    }
+
+    /**
+     * Prints the current state of the game board.
+     */
+    private static void printBoard() {
+        System.out.println();
+        for (char[] row : board) {
+            for (char c : row) System.out.print(c + " ");
+            System.out.println();
+        }
+        System.out.println();
+    }
+
+    /**
+     * Checks if the current player has won the game.
+     *
+     * @param player The player character ('X' or 'O')
+     * @return true if the player has won, false otherwise
+     */
+    private static boolean checkWin(char player) {
+        // Rows, columns, diagonals
+        for (int i = 0; i < 3; i++) {
+            if ((board[i][0] == player && board[i][1] == player && board[i][2] == player) ||
+                (board[0][i] == player && board[1][i] == player && board[2][i] == player)) {
+                return true;
+            }
+        }
+        return (board[0][0] == player && board[1][1] == player && board[2][2] == player) ||
+               (board[0][2] == player && board[1][1] == player && board[2][0] == player);
+    }
+}