58 lines
1.5 KiB
Python
58 lines
1.5 KiB
Python
#!/usr/bin/python
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# -*- coding: UTF-8 -*-
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# 棋盘尺寸
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BOARD_SIZE = 8
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solution_count = 0
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queen_list = [0] * BOARD_SIZE
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def eight_queens(cur_column: int):
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"""
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输出所有符合要求的八皇后序列
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用一个长度为8的数组代表棋盘的列，数组的数字则为当前列上皇后所在的行数
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:return:
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"""
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if cur_column >= BOARD_SIZE:
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global solution_count
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solution_count += 1
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# 解
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print(queen_list)
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else:
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for i in range(BOARD_SIZE):
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if is_valid_pos(cur_column, i):
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queen_list[cur_column] = i
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eight_queens(cur_column + 1)
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def is_valid_pos(cur_column: int, pos: int) -> bool:
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"""
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因为采取的是每列放置1个皇后的做法
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所以检查的时候不必检查列的合法性，只需要检查行和对角
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1. 行：检查数组在下标为cur_column之前的元素是否已存在pos
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2. 对角：检查数组在下标为cur_column之前的元素，其行的间距pos - QUEEN_LIST[i]
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和列的间距cur_column - i是否一致
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:param cur_column:
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:param pos:
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:return:
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"""
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i = 0
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while i < cur_column:
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# 同行
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if queen_list[i] == pos:
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return False
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# 对角线
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if cur_column - i == abs(pos - queen_list[i]):
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return False
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i += 1
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return True
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if __name__ == '__main__':
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print('--- eight queens sequence ---')
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eight_queens(0)
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print('\n--- solution count ---')
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print(solution_count)
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