Кужелев А.А. ЛР№2 Нахождение кратчайних путей в графе (Алгоритм Дейкстры) OpenMP версия

1706/kuzhelev_aa/main.cpp

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+#include <iostream>
+#include <chrono>
+#include <vector>
+#include <fstream>
+#include <iomanip>
+#include <random>
+#include <ctime>
+#include <string>
+#include <stdexcept>
+#include <omp.h>
+
+#define MAX_PATH 1000000000000000000
+
+void Generate_matrix(std::vector<int> &matr, int size) {
+	matr.resize(size*size);
+	int t = size;
+	std::mt19937 random(static_cast<unsigned int>(time(0)));
+	for (size_t i = 0; i + 1 < matr.size(); ++i) {
+		if (i%size == 0 && !i) {
+			++t;
+		}
+		if (i%t == 0 || matr[i]) {
+			continue;
+		}
+		matr[i] = random() % 1000;
+	}
+}
+
+void Print_Matrix(const std::vector<int> &matrix) {
+
+	int size = sqrt(matrix.size());
+	if (matrix.size() <= 900) {
+		for (int i = 0; i < matrix.size(); ++i) {
+			if (i%size == 0 && i) {
+				std::cout << std::endl;
+			}
+			std::cout << std::setw(5) << matrix[i] << " ";
+		}
+		std::cout << std::endl;
+	}
+	else {
+		std::ofstream ofs;
+		ofs.open("matrix.txt");
+		for (const auto &row : matrix) {
+			ofs << row << " ";
+
+		}
+		ofs << std::endl;
+	}
+}
+
+void Input_Matrix(std::vector<int> &matr, int size) {
+	int t = size;
+	matr.resize(size*size);
+	for (size_t i = 0; i < matr.size(); ++i) {
+		if (i%size == 0 && !i) {
+			++t;
+		}
+		if (i%t == 0) {
+			continue;
+		}
+		int num;
+		std::cerr << "Insert distance " << i + 1 << "-" << i * size + 1 << ":";
+		std::cin >> num;
+		matr[i*size] = num;
+
+	}
+}
+
+void Print_Vector(const std::vector<int>& vec) {
+	std::cout << vec[0] << ": ";
+	for (size_t i = 1; i < vec[vec.size() - 1]; ++i)
+		std::cout << vec[i] << " ";
+	std::cout << std::endl;
+}
+
+void Read_Matrix(std::vector<int> &matr, size_t size, const std::string &matr_info) {
+	matr.resize(size*size);
+
+	std::ifstream in;
+	in.open(matr_info);
+	int x, y, weight;
+	while (in >> x >> y >> weight) {
+		matr[x*size + y] = matr[y*size + x] = weight;
+	}
+	in.close();
+}
+
+void help(const char *name, const char *message) {
+	std::cout << "\n\n" << std::string(message) +
+		"\nThis is Dijkstra algorithm application.\n\n" +
+		"Please provide arguments in the following format:\n\n" +
+		"  $ " + name + "<matrix_size> <begin_index> <log_file_path> <save_file>\n\n" +
+		"Where <matrix_size> <begin_index> are integer numbers, " +
+		"and <log_file_path> and <save_file> are strings.\n";
+}
+
+uint64_t minDistance(std::vector<uint64_t> dist, std::vector<bool> visited) {
+	uint64_t min = UINT64_MAX, min_index;
+
+	for (size_t i = 0; i < visited.size(); ++i) {
+		if (!visited[i] && dist[i] <= min) {
+			min = dist[i];
+			min_index = i;
+		}
+	}
+	return min_index;
+}
+
+void PrintPath(const std::vector<int> &parent, int i) {
+	if (parent[i] == -1) {
+		return;
+	}
+	PrintPath(parent, parent[i]);
+	std::cout << " " << i;
+}
+
+void PrintSolution(const std::vector<uint64_t> &min_dist, const std::vector<int> &parent, const int &begin) {
+	std::cout << "Vertex" << std::setw(10) << "Distance" << std::setw(10) << "Path\n";
+	for (int i = 0; i < parent.size(); ++i) {
+		if (i == begin)continue;
+		std::cout << begin << " -> " << i << "\t" << min_dist[i] << "\t\t" << begin;
+		PrintPath(parent, i);
+		std::cout << std::endl;
+	}
+}
+
+void Sequence_Alg(const std::vector<int> &matr, std::vector<uint64_t> &min_path, std::vector<int> &parent) {
+	const int t = sqrt(matr.size());
+	std::vector<bool> visited(t, false);
+
+	for (int count = 0; count < t - 1; ++count) {
+		int u = minDistance(min_path, visited);
+
+		visited[u] = true;
+
+		for (int i = 0; i < t; ++i) {
+			if (!visited[i] && matr[u*t + i] && min_path[u] + matr[u*t + i] < min_path[i]) {
+				parent[i] = u;
+				min_path[i] = min_path[u] + matr[u*t + i];
+			}
+		}
+	}
+}
+
+int minDistanceOMP(std::vector<uint64_t> dist, std::vector<bool> visited) {
+	uint64_t min = UINT64_MAX, min_index;
+
+#pragma omp parallel
+	{
+		int local_min = UINT64_MAX, local_min_index;
+
+#pragma omp for
+		for (int i = 0; i < visited.size(); ++i) {
+			if (!visited[i] && dist[i] < local_min) {
+				local_min = dist[i];
+				local_min_index = i;
+			}
+		}
+#pragma omp critical
+		if (local_min < min) {
+			min = local_min;
+			min_index = local_min_index;
+		}
+	}
+
+	return min_index;
+}
+
+void OpenMP_Alg(const std::vector<int> &matr, std::vector<uint64_t> &min_path, std::vector<int> &parent) {
+	const int t = sqrt(matr.size());
+
+	std::vector<bool> visited(t, false);
+
+	for (int count = 0; count < t - 1; ++count) {
+		int u = minDistanceOMP(min_path, visited);
+		visited[u] = true;
+#pragma omp parallel for 
+		for (int i = 0; i < t; ++i) {
+			if (!visited[i] && matr[u*t + i] && min_path[u] + matr[u*t + i] < min_path[i]) {
+				min_path[i] = min_path[u] + matr[u*t + i];
+				parent[i] = u;
+			}
+		}
+	}
+}
+
+int main(int argc, char *argv[]) {
+	if (argc != 5) {
+		help(argv[0], "");
+		return 1;
+	}
+	int begin_index;
+	int t;
+	try {
+		t = std::stoi(argv[1]);
+		begin_index = std::stoi(argv[2]);
+	}
+	catch (std::invalid_argument) {
+		help(argv[0], "ERROR: Wrong matrix size value or begin index value.\n\n");
+		return 1;
+	}
+	if (begin_index >= t) {
+		help(argv[0], "ERROR: Wrong begin index value.\n\n");
+		return 1;
+	}
+	const std::string log = std::string(argv[3]);
+	const std::string info = std::string(argv[4]);
+	std::ofstream out(log);
+	std::vector<int> matr;
+
+
+	if (t < 1) {
+		help(argv[0], "ERROR: Size of matrix can't be less than 1.\\n");
+		return 1;
+	}
+	int key = 1;
+	if (t > 30)std::cout.rdbuf(out.rdbuf());
+	std::cerr << "Input matrix by yourself [1] [default]:\nGenerate matrix(Full graph) [2] :\n\nChoose one option:";
+	std::cin >> key;
+	switch (key) {
+	case 2:
+		Generate_matrix(matr, t);
+		break;
+	default:
+		Input_Matrix(matr, t);
+	}
+
+	std::vector<uint64_t> min_path(t, MAX_PATH);
+	std::vector<int> parent(t, -1);
+	Print_Matrix(matr);
+
+
+
+	min_path[begin_index] = 0;
+
+	auto begin = std::chrono::steady_clock::now();
+	Sequence_Alg(matr, min_path, parent);
+	auto end = std::chrono::steady_clock::now();
+
+	auto elapsed_ms = std::chrono::duration_cast<std::chrono::milliseconds>(end - begin);
+
+	std::vector<uint64_t> omp_min_path(t, MAX_PATH);
+	std::vector<int> omp_parent(t, -1);
+
+	omp_min_path[begin_index] = 0;
+
+	begin = std::chrono::steady_clock::now();
+	OpenMP_Alg(matr, omp_min_path, omp_parent);
+	end = std::chrono::steady_clock::now();
+
+	auto omp_elapsed_ms = std::chrono::duration_cast<std::chrono::milliseconds>(end - begin);
+	std::cout << "\n------------------------Sequence algorithm:------------------------\n";
+	PrintSolution(min_path, parent, begin_index);
+
+	std::cout << "\n------------------------OpenMP algorithm:------------------------\n";
+	PrintSolution(omp_min_path, omp_parent, begin_index);
+
+	std::cout << std::endl;
+	for (const auto row : min_path) {
+		std::cout << row << " ";
+	}
+	std::cout << std::endl;
+	std::ofstream out1(info);
+	out1 << matr.size() << " " << begin_index;
+	std::cerr << "Time spent to sequence algorithm:" << elapsed_ms.count() << " milliseconds" << std::endl;
+	std::cerr << "Time spent to OpenMP algorithm:" << omp_elapsed_ms.count() << " milliseconds" << std::endl;
+	return 0;
+}