ELI5: Explain Like I'm 5

Perfect hash function

Imagine that you have a big box full of different types of toys. Some toys are cars, some are dolls, and some are action figures. Now, let's say you want to organize these toys in a special way so that it is easy for you to find a specific toy.

What you can do is create a special system called a perfect hash function. This function is like a magical formula that gives each toy a unique number, or code, based on what type of toy it is. So, for example, all cars might have the code 1, all dolls might have the code 2, and all action figures might have the code 3.

Once you have this system set up, you can put each toy in a different box based on its code. All the cars go in one box labeled "Cars," all the dolls in another box labeled "Dolls," and so on. This way, when you want to play with a specific type of toy, you can easily find it by looking in the right box.

Now, let's say you get a new toy that is not a car, doll, or action figure. Maybe it's a puzzle. The perfect hash function will give this toy a new code that is different from 1, 2, or 3. Let's say the code for puzzles is 4. So, you would put this new toy in the box labeled "Puzzles."

The special thing about a perfect hash function is that it guarantees that no two toys will have the same code. This means that each toy will always have its own unique box, and you will never have to worry about mixing them up.

So, in summary, a perfect hash function is like a magical formula that gives each toy a special code based on its type. This makes it easy to organize the toys and find them when you want to play with them.