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add uniform int sequence with unique elements

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方而静 2023-07-19 18:33:19 +08:00
parent 650c363f03
commit b846678d29
2 changed files with 63 additions and 0 deletions
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1
libvmake/examples/random_numbers.cpp
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@ -4,6 +4,7 @@ using namespace std;
int main() {
vmake::outputln(cout, " ", vmake::take(vmake::rng::uniform_ints(1, 10), 15));
vmake::outputln(cout, " ", vmake::take(vmake::rng::uniform_ints(vmake::rng::require_unique, 1, 20), 15));
vmake::outputln(cout, " ", vmake::take(vmake::rng::uniform_reals(1., 10.), 5));
return 0;
}

62
libvmake/vmake.hpp
View File

@ -517,6 +517,68 @@ inline auto uniform_ints(Tval &&l, Tval &&r) {
});
}
struct require_unique_t {} require_unique;
namespace details {
template<typename Tval, typename Engine>
struct unique_ints_sequence {
using result = Tval;
unique_ints_sequence(unique_ints_sequence<Tval, Engine> &&) = default;
unique_ints_sequence(const unique_ints_sequence<Tval, Engine> &) = default;
Tval l, r;
Engine rng;
std::uniform_int_distribution<Tval> dis;
std::unordered_set<Tval> used;
std::vector<int> rest;
bool halfed;
unique_ints_sequence(Engine &&e, Tval &&l, Tval &&r) : l(l), r(r), rng(std::forward<Engine>(e))
, dis(std::forward<Tval>(l), std::forward<Tval>(r)), used(), rest(), halfed(false) {}
bool is_terminated() const noexcept {
return halfed && rest.empty();
}
auto operator()() {
if (!halfed && (used.size() + 1) * 2 >= static_cast<_unsigned_Tval>(r - l + 1)) {
for (Tval i = l; i <= r; ++i) {
if (!used.count(i)) rest.push_back(i);
}
std::shuffle(rest.begin(), rest.end(), rng);
halfed = true;
}
if (halfed) {
if (rest.empty()) throw sequence_terminated_error();
auto res = std::move(rest.back());
rest.pop_back();
return res;
}
while (true) {
auto res = dis(rng);
if (used.count(res)) continue;
used.insert(res);
return res;
}
}
private:
using _unsigned_Tval = typename std::conditional<std::is_integral<Tval>::value
, typename std::make_unsigned<Tval>::type, Tval>::type;
};
};
template<typename Tval = int, typename Engine = std::default_random_engine>
inline auto uniform_ints(require_unique_t _, Tval &&l, Tval &&r) {
return details::unique_ints_sequence<typename std::decay<Tval>::type, Engine>(Engine(make_seed())
, std::forward<Tval>(l), std::forward<Tval>(r));
}
template<typename Tval = double, typename Engine = std::default_random_engine>
inline auto uniform_reals(Tval &&l, Tval &&r) {
return generate([rng = Engine(make_seed())