Bin-packing-SA-solution/sa.hpp

#ifndef SIMULATED_ANNEALING_HEADER_12647_H
#define SIMULATED_ANNEALING_HEADER_12647_H

#define SIMULATED_ANNEALING_DISABLE_SHOWCRATES 1
#define SIMULATED_ANNEALING_DISABLE_SHOWITRNUM 2

#include <algorithm>
#include <iostream>
#include <random>
#include <set>
#include <vector>

namespace sa {

class box {
	std::multiset<long long> items;
	long long fullness{};

	friend void swap(box &one, box &two) {
		using std::swap;

		swap(one.items, two.items);
		swap(one.fullness, two.fullness);
	}

	public:

	box() = default;

	box(const std::multiset<long long> &multiset, long long fullness):
	    items(multiset), fullness(fullness) {}

	void add_item(long long item) {
		fullness += item;
		items.insert(item);
	}

	void clear() {
		items.clear();
		fullness = 0;
	}

	void pop() {
		fullness -= *items.begin();
		items.erase(items.begin());
	}

	auto swap10(box &other, int capacity) -> bool {
		if (*items.begin() + other.fullness > capacity) {
			return false;
		}
		other.add_item(*items.begin());
		pop(); return true; }

	auto swap11(box &other, int capacity) -> bool {
		long long choice1 = *items.begin();
		long long choice2 = *other.items.begin();

		if (choice1 + other.fullness - choice2 > capacity ||
		    choice2 + fullness - choice1 > capacity) {
		    	return false;
		}

		pop();
		other.pop();
		add_item(choice2);
		other.add_item(choice1);

		return true;
	}

	void print(int ind) const {
		std::cout << "Caixa " << ind << ":";
		for (auto item : items) {
			std::cout << ' ' << item;
		}
		std::cout << '\n';
	}

	[[nodiscard]] auto empty() const -> bool {
		return fullness == 0;
	}
};

class solution {
	std::vector<box> boxes;
	std::default_random_engine gen;
	int capacity;
	int fitness;
	int iterations;
	int iteration;

	friend void swap(solution &one, solution &two) {
		using std::swap;

		swap(one.boxes, two.boxes);
		swap(one.gen, two.gen);
		swap(one.capacity, two.capacity);
		swap(one.fitness, two.fitness);
		swap(one.iterations, two.iterations);
		swap(one.iteration, two.iteration);
	}

	public:
	solution() = default;

	solution(const solution &other, int itr): boxes(other.boxes), gen(other.gen),
	                                          capacity(other.capacity), fitness(other.fitness),
	                                          iteration(itr) {}

	solution(const std::vector<long long> &items, int capacity):  // Gera a solução inicial
	         gen(std::random_device()()), capacity(capacity),
	         iteration(0) {
		std::multiset<long long> its;
		for (auto i : items) {
			its.insert(i);
		}

		long long cap = capacity;
		box tmp;

		while (!its.empty()) {
			auto itr = its.upper_bound(cap);
			if (itr == its.begin()) {
	        		cap = capacity;
	        		cap -= *its.begin();
	        		itr = its.begin();
	        		this->boxes.emplace_back(tmp);
	        		tmp.clear();
			} else {
				itr--;
				cap -= *itr;
			}
			tmp.add_item(*itr);
			its.erase(itr);
		}

		if (!tmp.empty()) {
			this->boxes.emplace_back(tmp);
		}
		fitness = (int)this->boxes.size();
	}

	void setneighbor() { // Gera um vizinho da solução
		std::uniform_int_distribution<> dist(0, (int)boxes.size() - 1);

		int choice = dist(gen);
		std::vector<int> sequence(boxes.size() - 1);
		for (size_t i = 0; i < choice; i++) {
			sequence[i] = i;
		}
		for (size_t i = choice + 1; i < boxes.size(); i++) {
			sequence[i - 1] = i;
		}

		shuffle(sequence.begin(), sequence.end(), gen);

		for (auto ind : sequence) {
			if (boxes[choice].swap10(boxes[ind], capacity)) {
				if (boxes[choice].empty()) {
					boxes.erase(boxes.begin() + choice);
				}
				fitness = (int)boxes.size();
				return;
			}
		}

		for (auto ind : sequence) {
			if (boxes[choice].swap11(boxes[ind], capacity)) {
				return;
			}
		}
	}

	void randomize() {
		std::shuffle(boxes.begin(), boxes.end(), gen);
	}

	void print_sol(char flags = 0) const {
		if(!(flags & SIMULATED_ANNEALING_DISABLE_SHOWITRNUM)){
			std::cout << "Iteração da solução: " << iteration << '\n';
			std::cout << "Número de iterações calculadas: " << iterations << '\n';
		}
		std::cout << "Número de caixas: " << fitness << '\n';

		if(!(flags & SIMULATED_ANNEALING_DISABLE_SHOWCRATES)){
			for (size_t i = 0; i < boxes.size(); i++) {
				boxes[i].print((int)i + 1);
			}
		}
	}

	void setiterations(int itr) {
		iterations = itr;
	}

	static auto simulated_annealing(int capacity, const std::vector<long long> &items,
	                                double alpha, double temp,
	                                double temp_min) -> solution;
};

} // namespace sa

#endif