http://snippets.dzone.com/posts Fri, 10 Oct 2008 13:19:54 GMT DZone Snippets: permute code http://snippets.dzone.com/posts/show/2351 // description of your code here <br />Permute a list <br /> <br /><code> <br />cdef class Permute2: <br /> <br /> cdef int n, first <br /> cdef object lst <br /> <br /> def __init__(self, lst): <br /> self.lst = lst <br /> self.first = 0 <br /> self.n = len(lst) - 1 <br /> <br /> def __iter__(self): <br /> return self <br /> <br /> def __next__(self): <br /> cdef int j, l, k, x, y, z <br /> if self.first == 0: <br /> self.first = 1 <br /> return self.lst <br /> if self.n == 1: <br /> return [self.lst[1], self.lst[0]] <br /> while 1: <br /> if self.lst[-2] < self.lst[-1]: <br /> self.lst[-2], self.lst[-1] = self.lst[-1], self.lst[-2] <br /> elif self.lst[-3] < self.lst[-2]: <br /> if self.lst[-3] < self.lst[-1]: <br /> self.lst[-3], self.lst[-2], self.lst[-1] = self.lst[-1], self.lst[-3], self.lst[-2] <br /> else: <br /> self.lst[-3], self.lst[-2], self.lst[-1] = self.lst[-2], self.lst[-1], self.lst[-3] <br /> else: <br /> j = self.n - 3 <br /> if j < 0: raise StopIteration <br /> y = self.lst[j] <br /> x = self.lst[-3] <br /> z = self.lst[-1] <br /> while y >= x: <br /> j = j - 1 <br /> if j < 0: raise StopIteration <br /> x = y <br /> y = self.lst[j] <br /> if y < z: <br /> self.lst[j] = z <br /> self.lst[j+1] = y <br /> self.lst[self.n] = x <br /> else: <br /> l = self.n - 1 <br /> while y >= self.lst[l]: <br /> l = l - 1 <br /> self.lst[j], self.lst[l] = self.lst[l], y <br /> self.lst[self.n], self.lst[j+1] = self.lst[j+1], self.lst[self.n] <br /> k = j + 2 <br /> l = self.n - 1 <br /> while k < l: <br /> self.lst[k], self.lst[l] = self.lst[l], self.lst[k] <br /> k = k + 1 <br /> l = l - 1 <br /> return self.lst <br /></code> Tue, 01 Aug 2006 23:11:36 GMT http://snippets.dzone.com/posts/show/2351 llimllib (Bill Mill)