random_shuffle

prev_permutation

template <class BiIter>    bool prev_permutation(BiIter start, BiIter end); template <class BiIter, class Comp>     bool prev_permutation(BiIter start, BiIter end, Comp cmpfn);

The prev_permutation( ) algorithm constructs the previous permutation of a sequence. The permutations are generated assuming that a sorted sequence, from low to high, represents the first permutation. If the previous permutation does not exist, prev_permutation( ) sorts the sequence as its final permutation and returns false. Otherwise, it returns true.

The second form allows you to specify a comparison function that determines when one element is less than another.