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30 lines
887 B
Python
30 lines
887 B
Python
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import math
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def lexicographic_permutation(list, position):
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items = len(list)
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list = sorted(list)
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p = []
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position = position - 1
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while len(p) < items:
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index = 0
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# Find the next index to pop
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l = len(list) - 1
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f = math.factorial(l) if l else 0
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while position and position >= f:
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position = position - f
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index = index + 1
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p.append(list.pop(index))
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return p
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if __name__ == '__main__':
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print 'Testing permutations of 0..2:'
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list = [str(i) for i in [0, 1, 2]]
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for i in range(1, math.factorial(len(list)) + 1):
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p = lexicographic_permutation(list, i)
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print '\tPermutation', i, ''.join(p)
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list = [str(i) for i in [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]]
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p = lexicographic_permutation(list, 1000000)
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print '1 millionth lexicographic permutation of 0..9:', ''.join(p)
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