You are to write a program which takes in a pair of positive integers, n and m ,

Question

You are to write a program which takes in a pair of positive integers, n and m,

(0 < m _ n < 20), and outputs all the possible permutations of choosing m integers from the set f {1, 2, %u2026 , n}. The input is just one line with two integers separated by a white space. The output should print one permutation per line, and a final line containing the number of permutations printed.

Important:

Your program should prompt the user for input, and it should accept only valid input. Your output should be organized as follows:

Sample Input             Sample Output

3 2                               1 2

                                    1 3

                                    2 1

                                    2 3

                                    3 1

                                    3 2

                                    6

Explanation / Answer

#!/usr/bin/env python

def permutate(l, n, nl):

global count

if n == 0:

if len(nl) != len(set(nl)): return

nl1 = []

for i in nl: nl1.append(l[i])

print " ".join([str(x) for x in nl1])

count=count+1

else:

n = n - 1

nl1 = [x for x in nl]

for i in xrange(0, len(l)):

nl = [x for x in nl1]

nl.append(i)

permutate(l, n, nl)

del nl[:]

def permutations(l,m):

permutate(l,m , [])

n,m=raw_input("Enter integers n and m ").split()

count =0

permutations(range(1,int(n)+1),int(m))

print count

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