How can I solve the N-Queens problem in different programming languages?

How can I solve the N-Queens problem in different programming languages?

The N-Queens problem involves placing N queens on an N×N chessboard so that no two queens threaten each other. Would you like to see examples in specific languages?

Yes, can you show me how to implement it in Python?

Sure! Here's a simple backtracking solution in Python:

def solve_n_queens(n):
    def is_safe(board, row, col):
        for i in range(col):
            if board[row][i] == 1:
                return False
        for i, j in zip(range(row, -1, -1), range(col, -1, -1)):
            if board[i][j] == 1:
                return False
        for i, j in zip(range(row, n, 1), range(col, -1, -1)):
            if board[i][j] == 1:
                return False
        return True

    def solve(board, col):
        if col >= n:
            return True
        for i in range(n):
            if is_safe(board, i, col):
                board[i][col] = 1
                if solve(board, col + 1):
                    return True
                board[i][col] = 0
        return False

    board = [[0] * n for _ in range(n)]
    if not solve(board, 0):
        return []
    return board

This code defines a function to solve the N-Queens problem using backtracking.

That's great! Can you provide an example in Java as well?

Absolutely! Here's a Java implementation of the N-Queens problem:

public class NQueens {
    public static void solveNQueens(int n) {
        int[] board = new int[n];
        solve(board, 0);
    }

    private static void solve(int[] board, int row) {
        if (row == board.length) {
            printSolution(board);
            return;
        }
        for (int col = 0; col < board.length; col++) {
            if (isSafe(board, row, col)) {
                board[row] = col;
                solve(board, row + 1);
            }
        }
    }

    private static boolean isSafe(int[] board, int row, int col) {
        for (int i = 0; i < row; i++) {
            if (board[i] == col || 
                board[i] - i == col - row || 
                board[i] + i == col + row) {
                return false;
            }
        }
        return true;
    }

    private static void printSolution(int[] board) {
        for (int i = 0; i < board.length; i++) {
            for (int j = 0; j < board.length; j++) {
                if (board[i] == j) {
                    System.out.print("Q ");
                } else {
                    System.out.print(". ");
                }
            }
            System.out.println();
        }
        System.out.println();
    }
}

This code uses recursion to place queens on the board and checks for safety.