April 08, 2022

Divide and Conquer

“The trick is to find the simplicity inside the complexity.”
― Nick Wagner

Sometimes you run into what looks like a really difficult problem. How do you face that challenge? How can you find a solution? How can you beat it and actualy win?

I know there are a lot of problem-solving techniques, but when you’re facing the biggest problems, I believe there’s a very important, but often overlooked method that stands above the rest: divide and conquer.

Divide and conquer is a straightforward technique, but I’ve seen many people struggle for hours or even days before trying it. Like anything worth doing, it takes some practice to master, but you can get most of the benefits by simply remembering to use this approach.

So how do you use divide and conquer? It’s simple:

  1. Pause, think about the problem, and ask youself what problem you’re trying to solve.
  2. With the real problem identified, now you need to break it in to two pieces. If you’re not sure how to break it apart, ask yourself if there’s some way the problem could become easy.
  3. Now that you broke the problem into two pieces, think about the first piece. If it’s still intimidating, repeat this process for just that smaller problem. Otherwise solve it and go to the next problem.
  4. Repeat until the problem is solved.

Here’s a simple example using math (but you can do this for any challenge): x=91*17

  1. Well, the real problem is clear enough in this case. We need to find the value of x.
  2. It would be a lot nicer if we had something like 90*20 or 100*17. Can we do one of these? Yes: 91*17 = (100*17)-(9*17).
  3. First problem: 100*17=1700. Done.
  4. 9*17 would be easier if it was 10*17, so let’s make it 10*17-17.
  5. Second problem: 10*17=170.
  6. We now have x=1700-(170-17). That’s nice. No more multiplication.
  7. 170-17 would be easier if it was 170-20, so (170-20)+3.
  8. Third problem: 170-20=150.
  9. We now have x=1700-(150+3).
  10. This would be simpler as 1700-150-3.
  11. Fourth problem: 1700-150=1550.
  12. Now we only have x=1550-3.
  13. Fifth problem: 1550-3=1547.
  14. And we’re done: x=91*17=1547

This technique applies to a lot more than just math and the general idea apply to any problem that seems too big and complicated. Break it down, simplify the problem, and solve it one easy piece at a time.

Next time you find yourself facing an seemingly insurmountable challenge, try the divide and conquer technique.