• To write program to enter unique characters of string
• To be able to do permutations
• To practice solving problems using BTrees
• To practice writing solutions to problems in a clear and succinct way

Problem

You are required to construct a program that will perform the following sequence of operations:

• Reads a string and an integer, N, where the value of N is no larger than the number of characters in the string. (You may assume that the characters in the string are not repeated)
• Generate and output all possible N-character permutations of the characters in the string.

• Store the generated permutations, as they are calculated, in a 2-4 tree. Print the inorder traversal of the tree.

E.g.

Input AbdDC 2

Output

Ab, Ad, AD, AC, bA, bd, bD, bC, dA, db, dD, dC, DA, Db, Dd, DC, CA, Cb, Cd, CD