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50 lines
1.3 KiB
50 lines
1.3 KiB
# work5 八皇后问题
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# 在8乘8的国际象棋棋盘上，放8个皇后，皇后可以吃掉与之同行同列以及同一对角线上的其他皇后。
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# 为让她们共存，找出所有放置方法。
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n = 4
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queens = [-1]*n
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used_columns = set()
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used_left_diagonal = set()
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used_right_diagonal = set()
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def can_put_queen(row, col):
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return (col not in used_columns) and (row-col not in used_right_diagonal) and (row+col not in used_left_diagonal)
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def put_queen(row, col):
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queens.append((row, col))
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used_columns.add(col)
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used_right_diagonal.add(row-col)
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used_left_diagonal.add(row+col)
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def remove_queen(row, col):
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queens.remove((row, col))
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used_columns.remove(col)
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used_right_diagonal.remove(row-col)
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used_left_diagonal.remove(row+col)
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result = list()
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def queen(row: int) -> list[list[str]]:
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if row == n:
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rowText = ["."] * n
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board = list()
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for i in range(n):
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rowText[queens[i]] = "Q"
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board.append("".join(rowText))
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rowText[queens[i]] = "."
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result.append(board)
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for col in range(n):
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if not can_put_queen(row, col):
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continue
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queens[row] = col
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put_queen(row, col)
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queen(row+1)
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remove_queen(row, col)
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queen(0)
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for board in result:
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for row in board:
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print(row)
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print("------------") |