What's the meaning of SOLID

What're the main features of OOP

What's encapsulation? How is it work?

They are giving me three java classes at their doc file and giving answer them what's the object are valid or invalid

Showed a picture what's the meaning of this picture? It was a binary search tree and giving their explanation about how is it work and why is called a binary search tree

They are giving an array and said that what searching I can use to find a number easily.

Given five positive integers, find the minimum and maximum values that can be calculated by summing exactly four of the five integers. Then print the respective minimum and maximum values as a single line of two space-separated long integers. arr = [3,7,1,9,5] Output: 16 24