C++ Primer, Fifth Edition

A.2.7. Permutation Algorithms

The permutation algorithms generate lexicographical permutations of a sequence. These algorithms reorder a permutation to produce the (lexicographically) next or previous permutation of the given sequence. They return a bool that indicates whether there was a next or previous permutation.

To understand what is meant by next or previous permutaion, consider the following sequence of three characters: abc. There are six possible permutations on this sequence: abc, acb, bac, bca, cab, and cba. These permutations are listed in lexicographical order based on the less-than operator. That is, abc is the first permutation because its first element is less than or equal to the first element in every other permutation, and ...