Question

I need to generate a random maze with given width and height. I could do this in Perl with Depth-first search algorithm, in which I use 2D arrays, something like this:

    for my $i (0 .. $h - 1) {
        for my $j (0 .. $w - 1) {
            push @{ $cell[$i] }, '1';
        }
        push @{ $cell[$i] }, '0';
    }
    for my $i (0 .. $w) {
        $cell[$h][$i] = '';
    }

While in Objective C, there’s no 2D array. I’m kind of lost now. What is the equivalent of 2D array in Objective C so that I pretty much can use the same data structure as in Perl?
Thanks.

Answer 1

One way is to use Objective-C style array:

NSMutableArray *cell = [NSMutableArray arrayWithCapacity:h];
for (int i=0; i<h; ++i) {
    NSMutableArray *row = [NSMutableArray arrayWithCapacity:w];
    for (int j=0; j<w; ++j) {
        // use a random number
        [row addObject:[NSNumber numberWithInt:rand()]];
    }
    // add one row
    [cell addObject:row];
}

Another way is just to use C style array:

int **cell = malloc(h*sizeof(int *));
for (int i=0; i<h; ++i) {
    cell[i] = malloc(w*sizeof(int));
    for (int j=0; j<w; ++j) {
        cell[i][j] = rand();
    }
}

// after you used it remeber to free it
for (int i=0; i<h; ++i) {
    free(cell[i]);
}
free(cell);
cell = NULL;