Make use of an array named selected.
For i=1 to length of the string
select the first element which is not selected add it to the working string and increment the number of selected chars
if number of selected chars reaches length of string, print the working string
else, call the same function for next selection
before continuing to the next element in the for loop unselect this element and decrease the number of elements selected and remove the element from the working string
Non recursive method:
Use the next perm method using the indices.
Use a traversal ptr from the right.
Stop when a[i]<a[i+1]
find the smallest number x from a[i+1] to a[n] such that a[i]<x.
sort the remaining elements in the positions a[i+1]to a[n](including a[i]) in ascending order.