Permutations by swapping: Difference between revisions

===Python: simplerrecursive===

After spotting the pattern of highest number being inserted into each perm of lower numbers from right to left, then left to right, I developed this simpler iterativerecursive function:

def s_perm(items = [[]]):

for j in range(n) if items <= 0:

new_items = return [[]]

for i, item in enumerate(items)else:

ifnew_items i= % 2:[]

for i, item in #enumerate(s_perm(items step- down1)):

new_itemsif += [item[:i] +% [j] + item[i2:] \

# step for i in range(len(item), -1, -1)]down

# step up for i in range(len(item), -1, -1)]

new_items += [item[else:i] + [j] + item[i:] \

# step for i in range(len(item) + 1)]up

items = new_items += [item[:i] + [items - 1] + item[i:] \

for i, item in enumerate(itemss_perm(n))]</lang>