Efficient Iterator for Permutations and Combinations
Description
It helps in 1) generating permutations and combinations with or
without replacement; 2) with distinct items or non-distinct items (multiset);
3) calculating number of combinations or permutations in various situations. All
generated sequences are in lexicographical order (AKA, dictionary order). The
algorithms to generate permutations and combinations are memory efficient. These
iterative algorithms enable users to process all sequences without putting all
results in the memory at the same time. The algorithms are written in C/C++ for
faster performances.