A recursive approach (which is what I would use) would involve breaking the problem into isomorphic subproblems: to find all permutations of a string, find all permutations of the string without a ...

In this paper we consider the generation of permutations, i.e. all ordered n-tuples of different elements from the set An = {a₀, a₁, . . . , an-1} which is a combinatorial problem often occurring in ...