diff --git a/other/nqueens.py b/other/nqueens.py new file mode 100644 index 000000000..1b1c75878 --- /dev/null +++ b/other/nqueens.py @@ -0,0 +1,77 @@ +#! /usr/bin/python3 +import sys + +def nqueens(board_width): + board = [0] + current_row = 0 + while True: + conflict = False + + for review_index in range(0, current_row): + left = board[review_index] - (current_row - review_index) + right = board[review_index] + (current_row - review_index); + if (board[current_row] == board[review_index] or (left >= 0 and left == board[current_row]) or (right < board_width and right == board[current_row])): + conflict = True; + break + + if (current_row == 0 and conflict == False): + board.append(0) + current_row = 1 + continue + + if (conflict == True): + board[current_row] += 1 + + if (current_row == 0 and board[current_row] == board_width): + print("No solution exists for specificed board size.") + return None + + while True: + if (board[current_row] == board_width): + board[current_row] = 0 + if (current_row == 0): + print("No solution exists for specificed board size.") + return None + + board.pop() + current_row -= 1 + board[current_row] += 1 + + if board[current_row] != board_width: + break + else: + current_row += 1 + if (current_row == board_width): + break + + board.append(0) + return board + +def print_board(board): + if (board == None): + return + + board_width = len(board) + for row in range(board_width): + line_print = [] + for column in range(board_width): + if column == board[row]: + line_print.append("Q") + else: + line_print.append(".") + print(line_print) + + +if __name__ == '__main__': + default_width = 8 + for arg in sys.argv: + if (arg.isdecimal() and int(arg) > 3): + default_width = int(arg) + break + + if (default_width == 8): + print("Running algorithm with board size of 8. Specify an alternative Chess board size for N-Queens as a command line argument.") + + board = nqueens(default_width) + print(board) + print_board(board) \ No newline at end of file