3.Define Complexity. 4. Give any two examples of Computational Models. 5. Reasons for studying algorithms. 6. What is the job of Java compiler and interpreter? 2. In Java, if a method does not return a value, what type you specify in return. s. Does recursion use more memory, if yes justify the answer? 9. Explain the rules for defining a method in Java with example. 10. Difference between Linear and Binary recursion. 11. Difference between Top-Bottom and Bottom-Top approaches. 12. Difference between Worst-case and Average-case in algorithm