RogerBW's Blog

I’ve been doing the Weekly Challenges. The latest involved series multiplication and text fitting. (Note that this ends today.)

Task 1: Product Sign

You are given an array of @ints.

Write a script to find the sign of product of all integers in the given array. The sign is 1 if the product is positive, -1 if the product is negative and 0 if product is zero.

One obvious way to do this would be to calculate the product of the series (e.g. with a reduce-like function) and then apply what BASIC used to call SGN. But it occurred to me that I'm not being asked for the actual product, only its sign, so there's a less computationally intensive way of doing it. Kotlin:

fun productsign(a: List<Int>): Int {
    var out = 1
    for (t in a) {
        if (t < 0) {
            out = -out
        } else if (t == 0) {
            out = 0
        }
    }
    return out
}

In PostScript I can get away with no variables at all.

/productsign {
    1 exch
    {
        dup 0 lt {
            pop neg
        } {
            0 eq {
                pop 0
                exit
            } if
        } ifelse
    } forall
} bind def

Task 2: Line Counts

You are given a string, $str, and a 26-items array @widths containing the width of each character from a to z.

Write a script to find out the number of lines and the width of the last line needed to display the given string, assuming you can only fit 100 width units on a line.

Since I don't need to know the widths of the lines except for the last, I don't bother to record them; just track the current width and the total number of lines. Raku:

sub linecounts($a, @w) {
    my $linecount = 1;
    my $linewidth = 0;
    my $asize = ord('a');
    for $a.comb -> $c {
        my $wd = @w[ord($c) - $asize];
        if ($linewidth + $wd > 100) {
            $linecount++;
            $linewidth = $wd;
        } else {
            $linewidth += $wd;
        }
    }
    return [$linecount, $linewidth];
}

and all the other languages work essentially the same way.

Full code on github.