This repository contains a single-file header-only C++17 disjoint-set structure.
#include <unionfind/unionfind.hpp>
auto main(int argc, char **argv)-> int
{
// create a disjoint-set structure for 5 sets.
unionfind::UnionFind uf{5};
// merge sets 0 and 1
uf.merge(0, 1);
// merge sets 0 and 2
uf.merge(0, 2);
// find returns an std::optional which is std::nullopt if the passed argument is greater
// than the number of elements with which the UnionFind structure was created.
std::optional<std::size_t> zero_opt = uf.find(0);
assert(uf.find(0) ==uf.find(1));
assert(uf.find(1) ==uf.find(2));
// if it is known that the passed argument is in
// a valid range UnionFind::findUnsafe can be used instead
std::size_t zero = uf.findUnsafe(0);
// UnionFind::numberOfSets returns the number of disjoint sets in the datastructure
auto sets = uf.numberOfSets();
// uf contains 3 sets: {0, 1, 2}, {3}, {4}
assert(sets == 3);
}