# This program solves the Eight Queens problem.
# This version prints all solutions.

from ChessBoard import *

# Places queens on the given board,
# starting with the given column.
def place_queens(board, col = 0):
    if not board.valid():
        return
    elif col >= board.size():
        print(board)
    else:
        for row in range(board.size()):
            board.place(row, col)          # choose
            place_queens(board, col + 1)   # explore
            board.remove(row, col)         # un-choose
        return False

def main():
    size = int(input("Board size? "))
    board = ChessBoard(size)
    print("Here are all solutions:")
    place_queens(board)

main()