//
//  main.c
//  matrix_multiplication_with_threads
//
//  Created by Ahmed on 10/18/17.
//  Copyright © 2017 Abdellah. All rights reserved.
//

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

typedef long long ll;

struct Matrix {
    ll **mat;
    int n,m;

} a, b, res1, res2;


// this function to allocate matrix
void allocate(struct Matrix *a,int n,int m) {
    a->n = n , a->m = n;
    a->mat = (ll**) malloc(n*sizeof(ll*));
    for(int i=0; i < n ; ++i)
        a->mat[i] = (ll*) malloc(m*sizeof(ll));

    for(int i=0 ; i < n ; ++i)
        for (int j=0; j < m; ++j)
            a->mat[i][j] = 0;
}

// this struct for identifying the cell in method_1 thread
struct cell {
    int i,j;
};

// this method for computing the cell in (method_1)
void * compute_cell(void *args) {

    int i = ((struct cell*) args)->i , j = ((struct cell*) args)->j;
    printf("cell:%d %d\n",i,j);

    for(int k = 0; k < b.n ; ++k)
        res1.mat[i][j] += a.mat[i][k]*b.mat[k][j];

    pthread_exit(0);
}




// this funciton for calculating result matrix each elemnt in it copmuted in separate thread
void method_1 () {

    pthread_t threads[a.n][b.m];
    for(int i=0 ; i < a.n ; ++i) {
        for (int j=0; j < b.m ; ++j) {
            struct cell* args = (struct cell*) malloc(sizeof(struct cell));
            args->i = i , args->j = j;
            pthread_attr_t attr;
            pthread_attr_init(&attr);
            int rc = pthread_create(&threads[i][j], &attr, compute_cell, (void*) args);
            if(rc)
                printf("Error, happened in creating thread int Method_1 cell:%d %d and returns %d.",i,j,rc);
            free(args);
        }
    }

    // finish each thread and each cell in matrix
    for(int i=0 ; i < a.n ; ++i)
        for (int j=0; j < b.m; ++j)
            pthread_join(threads[i][j], NULL);

}


// this function for computing the roww in (method_2)
void *compute_row (void *args) {

    int *row = (int*) args;

    for(int j=0 ; j < b.m ; ++j)
        for(int k=0 ; k < b.n ; ++k)
            res2.mat[*row][j] += a.mat[*row][k]*b.mat[k][j];

    pthread_exit(0);
}

// this function for calculating result matrix each row in it computed in separate thread
void method_2 () {
    pthread_t threads[a.n];

    for(int i=0; i < a.n ;++i) {
        int args = i;
        pthread_attr_t attr;
        pthread_attr_init(&attr);
        int rc = pthread_create(&threads[i], &attr, compute_row, &args);
        if(rc)
            printf("Error, happened in creating thread int Method_2 row:%d and returns %d.",i,rc);

    }
    // finish each threa and each row in matrix
    for (int i=0; i < a.n ; ++i)
        pthread_join(threads[i], NULL);

}

// this function for reading and allocating each matrix
void read_matrix(struct Matrix *a) {
    int n,m;
    scanf("%d%d",&n,&m);

    allocate(a,n,m);

    for(int i=0; i < a->n ; ++i)
        for(int j=0 ; j < a->m ; ++j)
            scanf("%lld",&a->mat[i][j]);

}

void print(struct Matrix *a) {
    for(int i=0; i < a->n ; ++i) {
        for(int j=0 ; j < a->m ; ++j)
            printf("%lld\t",a->mat[i][j]);
        printf("\n");
    }
}

void true_ans() {

    printf("---------- true answer ----------\n");
    for(int i=0;i<a.n;++i){
        for(int j=0;j<b.m;++j){
            ll cell = 0;
            for(int k=0;k<b.n;++k) cell += a.mat[i][k]*b.mat[k][j];
            printf("%lld\t",cell);
        }
        printf("\n");
    }
}
int main(int argc, const char * argv[]) {


    read_matrix(&a) , read_matrix(&b);
    allocate(&res1, a.n, b.m) , allocate(&res2, a.n, b.m);
    printf("Method_ 1:\n");
    method_1() , print(&res1);
    printf("Method_ 2:\n");
    method_2() , print(&res2);
    true_ans();
    return 0;
}