Data_Structure/作業/unit1/matrix multiplication/by_me.c

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

void mul(int **a ,int **b,int **c ,int m , int k ,int n){
	int i , j , l ,sum;
	
	for (i=0;i<m;i++){
		for(j=0;j<n;j++){
			sum = 0;
			for(l=0;l<k;l++){
				sum += a[i][l]*b[l][j];
			}c[i][j]=sum; 
		}
	}
}

int main(){
	int i , j ,m=2,k=3,n=4;
	
	int a[2][3]={{1,2,7},{3,4,1}};
	int b[3][4]={{5,6,2,4},{7,8,2,4},{7,2,6,1}};

	
	int **arr_a = (int**)malloc(m * sizeof(int*));
	int **arr_b = (int**)malloc(k * sizeof(int*));
	int **arr_c = (int**)malloc(m * sizeof(int*));
	for(i=0;i<m;i++){
		arr_a[i] = (int*)malloc(k*sizeof(int));		
		arr_c[i] = (int*)malloc(n*sizeof(int));
	}
	for(i=0;i<k;i++){
		arr_b[i] = (int*)malloc(n*sizeof(int));
	}
	
	for (i=0;i<m;i++){
		for(j=0;j<k;j++){
			arr_a[i][j]=a[i][j];		
		}
	}
	for (i=0;i<k;i++){
		for(j=0;j<n;j++){
			arr_b[i][j]=b[i][j];		
		}
	}
	
	
	mul(arr_a,arr_b,arr_c,m,k,n);
	
	for (i=0;i<m;i++){
		for(j=0;j<n;j++){
			printf("c[%d][%d]=%d\n",i,j,arr_c[i][j]);
		}
	}
	
	
	free (arr_a);
	free (arr_b);
	free (arr_c);
	
	for(i=0;i<m;i++){
		free (arr_a[i]);
		free (arr_c[i]);
	}
	for(i=0;i<k;i++){
		free (arr_b[i]);
	}
	
	return 0 ;
}