Solution.py

def print_solution(board, n):
    for row in board:
        print(" ".join("Q" if col else "." for col in row))
    print()

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

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

def solve_n_queens(n):
    board = [[0] * n for _ in range(n)]
    if not solve_n_queens_util(board, 0, n):
        print("No solution exists.")
        return
    print_solution(board, n)

if __name__ == "__main__":
    n = int(input("Enter the size of the board (N): "))
    solve_n_queens(n)