forked from colonelpanic/dotfiles
69 lines
1.7 KiB
Python
Executable File
69 lines
1.7 KiB
Python
Executable File
#!/usr/bin/env python
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import sys
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class KnightMoves(object):
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deltas = [(1, 2), (2, 1), (-1, 2), (-2, 1),
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(1, -2), (2, -1), (-1, -2), (-2, -1)]
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max_x = 8
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max_y = 8
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def count_knight_moves(self, start, end):
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this_generation = [start]
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move_count = 0
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seen = set()
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while True:
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for position in this_generation:
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if position in seen:
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continue
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elif position == end:
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return move_count
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else:
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seen.add(position)
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this_generation = list(self.generate_moves_from_generation(this_generation))
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move_count += 1
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def generate_moves_from_generation(self, previous_generation):
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return (
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position
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for ancestor in previous_generation
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for position in self.generate_moves_from_position(ancestor)
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)
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def generate_moves_from_position(self, position):
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x, y = position
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return (
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(x + delta_x, y + delta_y)
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for delta_x, delta_y in self.deltas
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if self.in_bounds(x + delta_x, y + delta_y)
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)
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def in_bounds(self, x, y):
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return 0 <= x < self.max_x and 0 <= y < self.max_y
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def file_to_index(file_char):
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assert 'a' <= file_char <= 'h'
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return ord(file_char) - 97
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def rank_to_index(rank):
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assert 0 < int(rank) <= 8
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return int(rank) - 1
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def square_name_to_indices(square_name):
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file_char, rank_char = square_name
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return rank_to_index(int(rank_char)), file_to_index(file_char)
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if __name__ == '__main__':
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print KnightMoves().count_knight_moves(
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square_name_to_indices(sys.argv[1]),
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square_name_to_indices(sys.argv[2])
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)
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