Files
advent-of-code/2021/puzzle-22-01.cc

85 lines
2.3 KiB
C++

#include <array>
#include <iostream>
#include <regex>
#include <string>
using Int = long;
struct Pos
{
constexpr Pos(Int x, Int y, Int z) : x_(x), y_(y), z_(z) {}
[[nodiscard]] constexpr auto x() const noexcept -> Int { return x_; }
[[nodiscard]] constexpr auto y() const noexcept -> Int { return y_; }
[[nodiscard]] constexpr auto z() const noexcept -> Int { return z_; }
private:
Int x_{0};
Int y_{0};
Int z_{0};
};
constexpr auto operator==(Pos const& lhs, Pos const& rhs) -> bool
{
return lhs.x() == rhs.x() && lhs.y() == rhs.y() && lhs.z() == rhs.z();
}
constexpr auto operator<(Pos const& lhs, Pos const& rhs) -> bool
{
return lhs.x() < rhs.x() ||
(lhs.x() == rhs.x() && (lhs.y() < rhs.y() || (lhs.y() == rhs.y() && lhs.z() < rhs.z())));
}
struct State
{
void set(Pos const& from, Pos const& to) { set(from, to, true); }
void clear(Pos const& from, Pos const& to) { set(from, to, false); }
[[nodiscard]] constexpr auto size() const noexcept
{
return std::count(nodes_.begin(), nodes_.end(), true);
}
private:
constexpr static Int min_coord{-50};
constexpr static Int max_coord{50};
constexpr static Int width{max_coord - min_coord + 1};
void set(Pos const& from, Pos const& to, bool value)
{
for (auto x{std::max(min_coord, from.x())}; x <= std::min(max_coord, to.x()); ++x) {
for (auto y{std::max(min_coord, from.y())}; y <= std::min(max_coord, to.y()); ++y) {
for (auto z{std::max(min_coord, from.z())}; z <= std::min(max_coord, to.z()); ++z) {
nodes_[(x - min_coord) * width * width + (y - min_coord) * width + (z - min_coord)] =
value;
}
}
}
}
std::array<bool, (width * width * width)> nodes_{false};
};
auto main() -> int
{
std::regex re{R"((on|off) x=(-?\d+)..(-?\d+),y=(-?\d+)..(-?\d+),z=(-?\d+)..(-?\d+))"};
std::string line;
State state;
while (std::getline(std::cin, line) && !line.empty()) {
std::smatch m;
if (!std::regex_search(line, m, re)) {
std::cout << "Unable to match: " << line << '\n';
return 1;
}
Pos from{std::stol(m.str(2)), std::stol(m.str(4)), std::stol(m.str(6))};
Pos to{std::stol(m.str(3)), std::stol(m.str(5)), std::stol(m.str(7))};
if (m.str(1) == "on") {
state.set(from, to);
}
else {
state.clear(from, to);
}
}
std::cout << "Number lit: " << state.size() << '\n';
}