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#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <time.h>

#define MAX 4096
#define MAX_THREADS 8

int A[MAX][MAX], B[MAX][MAX], C[MAX][MAX];
int size, thread_count;

void fill_matrix(int size) {
    for (int i = 0; i < size; i++)
        for (int j = 0; j < size; j++) {
            A[i][j] = rand() % 10;
            B[i][j] = rand() % 10;
        }
}

void* multiply_parallel(void* arg) {
    int tid = *(int*)arg;
    int from = (tid * size) / thread_count;
    int to = ((tid + 1) * size) / thread_count;

    for (int i = from; i < to; i++)
        for (int j = 0; j < size; j++) {
            C[i][j] = 0;
            for (int k = 0; k < size; k++)
                C[i][j] += A[i][k] * B[k][j];
        }

    pthread_exit(0);
}

int main() {
    int sizes[] = {128, 256, 512, 1024, 2048, 4096};
    thread_count = MAX_THREADS;

    for (int s = 0; s < 6; s++) {
        size = sizes[s];
        fill_matrix(size);

        pthread_t threads[MAX_THREADS];
        int thread_ids[MAX_THREADS];

        clock_t start = clock();
        for (int i = 0; i < thread_count; i++) {
            thread_ids[i] = i;
            pthread_create(&threads[i], NULL, multiply_parallel, &thread_ids[i]);
        }
        for (int i = 0; i < thread_count; i++)
            pthread_join(threads[i], NULL);
        clock_t end = clock();

        double time_taken = (double)(end - start) / CLOCKS_PER_SEC;
        printf("Parallel Time for %dx%d: %.4f seconds\n", size, size, time_taken);
    }

    return 0;
}