7672049e1c
After a five year hiatus, I decided to attempt to solve the famous N queens problem again. This time, instead of modeling the chess board using a `[[Bool]]`, I'm using `[Integer]` where the `Integer` indicates which column has a queen. This is a bit lighter in RAM.
46 lines
1 KiB
Python
46 lines
1 KiB
Python
def print_board(board):
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result = []
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for row in range(8):
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r = []
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for col in range(8):
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r.append("X" if col == board[row] else "-")
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result.append(" ".join(r))
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print("\n".join(result))
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print()
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def can_place(board, row, col):
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column_occupied = not any([board[i] == col for i in range(row)])
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diagonals_clear = True
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for r in range(row):
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w = abs(col - board[r])
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h = abs(r - row)
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if w == h:
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diagonals_clear = False
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break
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return all([column_occupied, diagonals_clear])
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def init_board():
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board = []
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for row in range(8):
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board.append(None)
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return board
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def copy_board(board):
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return board[:]
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def n_queens():
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do_n_queens(init_board(), 0, 0)
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def do_n_queens(board, row, col):
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if row == 8:
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print_board(board)
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return
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for i in range(col, 8):
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if can_place(board, row, i):
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copy = copy_board(board)
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copy[row] = i
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do_n_queens(copy, row + 1, 0)
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n_queens()
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