2. Let A = {a1, . . . , an } and B = {b1, . . . , bm } be two sets of numbers. Consider the problem of finding their intersection, i. e., the set C of all the numbers that are in both A and B. a. Design a brute-force algorithm for solving this problem and determine its efficiency class. b. Design a presorting-based algorithm for solving this problem and determine its efficiency class.

Use a physical stopwatch to record the length of time it takes to run the program. calculate the difference obtained by calls to the method system. currenttimemillis() just before the start of the algorithm and just after the end of the algorithm. calculate the difference obtained by calls to the method system. currenttimemillis() at the start of the program and at the end of the program so that the elapsed time includes the display of the result. use the value returned by the method system. currenttimemillis() just after the end of the algorithm as the elapsed time.