import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class MatrixMultiplier {
    private final int[][] matrixA;
    private final int[][] matrixB;
    private final int[][] result;
    private final int size;

    public MatrixMultiplier(int size) {
        this.size = size;
        this.matrixA = generateMatrix(size);
        this.matrixB = generateMatrix(size);
        this.result = new int[size][size];
    }

    private int[][] generateMatrix(int size) {
        int[][] matrix = new int[size][size];
        for (int i = 0; i < size; i++) {
            for (int j = 0; j < size; j++) {
                matrix[i][j] = (int) (Math.random() * 10);
            }
        }
        return matrix;
    }

    public void multiplySequential() {
        for (int i = 0; i < size; i++) {
            for (int j = 0; j < size; j++) {
                for (int k = 0; k < size; k++) {
                    result[i][j] += matrixA[i][k] * matrixB[k][j];
                }
            }
        }
    }

    public void multiplyParallel(int numThreads) throws InterruptedException {
        if (numThreads == 1) {
            multiplySequential();
            return;
        }

        ExecutorService executor = Executors.newFixedThreadPool(numThreads);
        int chunkSize = (int) Math.ceil((double) size / numThreads);

        for (int thread = 0; thread < numThreads; thread++) {
            final int startRow = thread * chunkSize;
            final int endRow = Math.min(startRow + chunkSize, size);

            executor.submit(() -> {
                for (int i = startRow; i < endRow; i++) {
                    for (int j = 0; j < size; j++) {
                        for (int k = 0; k < size; k++) {
                            result[i][j] += matrixA[i][k] * matrixB[k][j];
                        }
                    }
                }
            });
        }
        executor.shutdown();
        executor.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS);
    }

    private void resetResult() {
        for (int i = 0; i < size; i++) {
            Arrays.fill(result[i], 0);
        }
    }

    static class Result {
        int threads;
        long time;

        Result(int threads, long time) {
            this.threads = threads;
            this.time = time;
        }
    }

    public static void main(String[] args) throws InterruptedException {
        int[] matrixSizes = {100, 300, 500};
        int[] threadCounts = {1, 2, 4, 6, 8, 10};
        int runs = 5; // количество прогонов

        for (int size : matrixSizes) {
            System.out.println("\nРазмер матрицы: " + size + "x" + size);
            MatrixMultiplier multiplier = new MatrixMultiplier(size);
            List<Result> results = new ArrayList<>();

            for (int threads : threadCounts) {
                long totalDuration = 0;

                for (int run = 0; run < runs; run++) {
                    multiplier.resetResult();
                    long startTime = System.nanoTime();
                    multiplier.multiplyParallel(threads);
                    long endTime = System.nanoTime();

                    totalDuration += (endTime - startTime);
                }

                long averageDuration = totalDuration / runs;
                results.add(new Result(threads, averageDuration));
            }

            // Сортировка по времени выполнения
            results.sort(Comparator.comparingLong(r -> r.time));

            System.out.println("Результаты (среднее время за " + runs + " прогонов):");
            for (Result result : results) {
                System.out.printf("Потоки: %d, среднее время: %d нс\n", result.threads, result.time);
            }
        }
    }
}