The problem is to implement a function that outputs all possible permutations of the characters in a string. Unlike combinations, two permutations are considered distinct if they contain the same characters, but in a different order. Also, for the purposes of this exercise, each occurrence of a repeated character is considered to be a distinct character. That is, if the input is “aaa”, the output should be six repetitions of “aaa”. The permutations may be output in any order.
This exercise, like the previous one on combinations of a string, is from the book Programming Interviews Exposed