Do It The Dumb Way

There's so much to like in the shape drawing lessons I talked about in my refactoring post that I thought I'd share a little more here.

It can be argued that the most important things for a program to do is work. The most clever, elegant, creative program is worthless if it doesn't produce the desired result. All too often, beginners and hot shot beginners in particular try to be too clever too early and get themselves into trouble.

When doing the shape drawing lessons the first couple of shape are pretty easy

| ****            |    | *               |
| ****            |    | **              |
| ****            |    | ***             |
| ****            |    | ****            |
| ****            |    |                 |
|                 |    |                 |

but things get more interesting with the right justified triangle:

----*       *
---**      **
--***     ***
-****    ****
*****   *****

For this triangle, students want to come up with the formula for the number of spaces. They usually figure out something like this with h-i-1 spaces and i+1 stars:

std::string tri2(int h){
    std::string r = "";
    for (int i = 0; i < h; ++i) {
      r = r + line(h-i-1,"-") + line(i+1,"*") + "\n";
    }
    return r;
  }

The formulas become harder to figure out as the shapes become more complex and sometimes students get stymied.

The truth is that while they're struggling to find the perfect solution, it's sometimes better to do it the dumb way.

Consider drawing a trapezoid like this example of height 5 and starting width 12:

************
 **********
  ********
   ******
    ****

A student could come up with the "formulas" for spaces and stars but sometimes there's a more straightforward way.

Consider the number of spaces on each line on the left hand side of the shape. First line is 0 then 1, 2 etc. Why not start a variable spaces at 0 and increment it on each loop iteration.

For the number of stars, it's starting at the width and being reduced by 2 each time.

This leads to a solution similar to this (using the line routine from the earlier refactoring post):

std::string trap(int height, int width){
  std::string r = "";

  int spaces = 0;
  int stars = width;
  for (int i = 0 ; i < height; ++i) {
    r = r + line(spaces," ") + lines(stars,"*") + "\n";
    spaces = spaces + 1;
    stars = stars - 2;
  }
  return r;
}

This solution is simple to construct, simple to understand, and quite frankly, hard to get wrong.

It can also lead a student to discovering a pattern or "formula" such as what was used to solve the earlier problems.

This might seem to some as a cheap way out, the dumb approach - creating extra variables and have them count along the way but I don't. There's nothing wrong with simple and straightforward. Yes, you could come up with an elegant formula but the bottom line is you need something to count 0,1,2,3… so create a variable to do it. You need something to count 12,10,8,… create one for that as well.

Now, I'm not advocating writing 100 if statements rather than a loop but I think you get the idea.

The best solution is one that works and Sometimes the "dumb" approach is the best approach.