PHP Taskbook Level 4.3

Make a function that will take an array as a parameter and remove all duplicates from it.

Make a function that will take an array as a parameter and remove from it all duplicates that occur more than three times.

Make a function that will take an array as a parameter and remove identical, adjacent elements from it.

Create a function that takes an array of numbers as a parameter and returns the maximum and minimum values ​​from that array as the following array: