20 lines
516 B
Python
20 lines
516 B
Python
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# permutations: no repeat characters
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def char_and_rest(i, xs):
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return xs[i], xs[0:i] + xs[i + 1:]
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def permutations(xs):
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if len(xs) == 1:
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return [xs]
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result = []
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for c, rest in [char_and_rest(i, xs) for i in range(len(xs))]:
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result += [c + perm for perm in permutations(rest)]
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return result
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expected = ["cat", "cta", "act", "atc", "tca", "tac"]
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result = permutations("cat")
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print(result, expected)
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assert len(result) == len(expected)
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assert result == expected
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print("Success!")
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