Background
When I learned to code, I hadn’t slept in a math classroom in 14 years.
I studied philosophy and taught courses on Symbolic Logic. I can talk about deductive proofs for days, but when people pull out a f of n’s… x²…_ [insert Greek letter] — _I nod along, but trust me, I have no idea what’s happening.
For this reason, I got a huge boost of empowerment when I figured out an algorithm question asking, “How can you determine the mathematical combination (nCr) of two numbers?”
If you’re like ‘what the…?’, then hell yeah, you are me a day ago. Let’s go!
The Meat
Defining the Problem
I’ll try my best to explain a combination:
Imagine you’re losing a high stakes poker game. You have sweat on your neck as a couple Mafia grunts stare daggers at you. As the big one cracks his knuckles, you think “It’s a shame I never learned to count cards. But maybe start now?”
Your mind is racing. You start thinking, how do I start? How many possible hands are there in the deck? Well, there are 52 cards. You get 5 distinct cards in each hand, and they can come in any order. Let’s see, some quick math in your head and…
Yeah, the answer is not obvious. But, you’re attempting a combination. A combination is when you have a collection of items and you want to find all the possible selections from that collection — for example, every possible hand from a deck of cards.
By the way, the answer is 2,598,960. Each hand has a 1/2,598,960th chance of being drawn. With numbers that big, it’s good we can train a computer to solve the problem.
#ruby #combination #ruby-on-rails #algorithms #dev #algorithms
