itertools.permutations()

This tool returns successive  length permutations of elements in an iterable.

If r is not specified or is None, then r defaults to the length of the iterable, and all possible full length permutations are generated.

Permutations are printed in a lexicographic sorted order. So, if the input iterable is sorted, the permutation tuples will be produced in a sorted order.

_{Sample Code}

>>> from itertools import permutations
>>> print permutations(['1','2','3'])
<itertools.permutations object at 0x02A45210>
>>> 
>>> print list(permutations(['1','2','3']))
[('1', '2', '3'), ('1', '3', '2'), ('2', '1', '3'), ('2', '3', '1'), ('3', '1', '2'), ('3', '2', '1')]
>>> 
>>> print list(permutations(['1','2','3'],2))
[('1', '2'), ('1', '3'), ('2', '1'), ('2', '3'), ('3', '1'), ('3', '2')]
>>>
>>> print list(permutations('abc',3))
[('a', 'b', 'c'), ('a', 'c', 'b'), ('b', 'a', 'c'), ('b', 'c', 'a'), ('c', 'a', 'b'), ('c', 'b', 'a')]

Task

You are given a string S.
Your task is to print all possible permutations of size k of the string in lexicographic sorted order.

Input Format

A single line containing the space separated string S and the integer value k.

Constraints

0 < k ≤ len(S)
The string contains only UPPERCASE characters.

Output Format

Print the permutations of the string S on separate lines.

Sample Input

HACK 2

Sample Output

AC
AH
AK
CA
CH
CK
HA
HC
HK
KA
KC
KH

Explanation

All possible size 2 permutations of the string “HACK” are printed in lexicographic sorted order.

Solution Implementation

# Python > Itertools > itertools.permutations()
# Find all permutations of a given size in a given string.
#
# https://www.hackerrank.com/challenges/itertools-permutations/problem
#

from itertools import permutations

s, n = input().split()
for i in permutations(sorted(s), int(n)):
    print("".join(i))