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# Another Pyrex Permutation Generator

```// description of your code here

```
cdef class PermuteJ:

cdef int n, first
cdef int lst3[32]
cdef object lst, lst2

def __init__(self, lst):
cdef int i
self.lst = lst
self.lst2 = lst[:]
self.first = 0
self.n = len(lst) - 1
if self.n >= 31:
raise Exception, "Are you kidding?"
for i from 0 <= i < len(lst):
self.lst3[i] = i

def __iter__(self):
return self

def __next__(self):
cdef int j, l, k, x, y, z, sn, length, neg1, neg2, neg3
cdef int* sl
cdef object output

if self.first == 0:
self.first = 1
return self.lst2
if self.n == 1:
return [self.lst[1], self.lst[0]]

sn = self.n
length = sn + 1
sl = self.lst3
neg1 = sn
neg2 = length - 2
neg3 = length - 3
while 1:
if sl[neg2] < sl[neg1]:
sl[neg2], sl[neg1] = sl[neg1], sl[neg2]
elif sl[neg3] < sl[neg2]:
if sl[neg3] < sl[neg1]:
sl[neg3], sl[neg2], sl[neg1] = sl[neg1], sl[neg3], sl[neg2]
else:
sl[neg3], sl[neg2], sl[neg1] = sl[neg2], sl[neg1], sl[neg3]
else:
j = sn - 3
if j < 0: raise StopIteration
y = sl[j]
x = sl[neg3]
z = sl[neg1]
while y >= x:
j = j - 1
if j < 0: raise StopIteration
x = y
y = sl[j]
if y < z:
sl[j] = z
sl[j+1] = y
sl[sn] = x
else:
l = neg2
while y >= sl[l]:
l = l - 1
sl[j], sl[l] = sl[l], y
sl[sn], sl[j+1] = sl[j+1], sl[sn]
k = j + 2
l = neg2
while k < l:
sl[k], sl[l] = sl[l], sl[k]
k = k + 1
l = l - 1

lst = self.lst
lst2 = self.lst2
for j from 0 <= j < length:
lst2[j] = sl[j]

return lst2

``````
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