Algorithm to generate all combinations of a string

Question

I found a link online that shows an algorithm to generate all combinations of a string: http://www.mytechinterviews.com/combinations-of-a-string

Algorithm is copied belo

Answer 1

The call of outstr.deleteCharAt counters the effect of outstr.append by deleting the last character of the outstr.

Each loop iteration proceeds as follows:

1. append a character
2. print the result
3. perform a recursive invocation at the level i+1
4. remove the character we added at step 1