问C语言中的图像腐蚀技术

EN

1  //N
4  //H
4  //L
....
.###
####
####

and the output is 
....
....
.##.
....

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

//test wether a pixel is surrounded by 4 '#' characters
char test(int i, int j,int H, int L, char c[H][L]){

    int k=0;
    int l=0;
    char result='-';
    if((i==0)||(i==H-1)||(j==0)||(j==L-1)){
        result='+';
    }
    else{

    for(k=0;k<2;k++){
        for(l=0;l<2;l++){
              if(c[i+(1-2*k)*l][j+(1-2*k)*(1-l)] =='.'){
                result='+';

                break;
            }

            else{

            }
        }
        if(result=='+'){break;}
        else{}
    }
    }

    return result;
}


//The erode function that replaces the image by one in which '#' characters are replaced by '.' characters when it is not surrounded by 4 '#' characters

char **erode(int H, int L, char c[H][L]){

    int i;
    int j;
    char ch='-';

    char **d = malloc (H * sizeof (int *));

    for (i = 0; i < H; i++) {
        d[i] = malloc (L * sizeof (int));
    }

    i=0;

    for (i=0;i<H;i++)
    {
        for (j=0;j<L;j++)
        {
            ch=test(i,j,H,L,c);

            if(ch=='+'){

                d[i][j]='.';

            }
            else{
                d[i][j]=c[i][j];
            }
            ch='-';
        }

    }


for (i= 0; i < H; i++) {
        free(d[i]);
       }
       free(d);

    return d;

}


//here are computed the inputs and outputs
int main()
{   

    int i=0;
    int j=0;


    int N;
    int H;
    int L;
    char o;

    scanf("%d",&N);
    scanf("%d",&H);
    scanf("%d",&L);
    scanf("%c",&o);

    char c[H][L];
    char d[H];
    char ero[H][L];


    while (i<H)
    {
        while (j<L)
        {
            scanf("%c",&c[i][j]);
            j++;
        }
        j=0;
        scanf("%c",&d[i]);
        i++;
    }

    int l;
    int m;
    int n;





    for(l=0;l<N;l++){
    for (i=0;i<H;i++)
    {
        for (j=0;j<L;j++)
        {
        ero[i][j]=erode(H,L,c)[i][j];

        }

    }
        for (m=0;m<H;m++)
        {
            for (n=0;n<L;n++){
                c[m][n]=ero[m][n];
            }

        }

    }


    for (i=0;i<H;i++)
     {
         for (j=0;j<L;j++){
             printf("%c",c[i][j]);
         }
         printf("\n");
     }

}