The answer is just a few lines for each and can be explained in a step by step process. Then efficiency please.

1. (20 points) Let A an Bb, and C fe...n) be three sets of numbers. Consider the problem of finding their intersection, i.e., the set D of all the numbers that are in A, B, and C. . Design a brute-force algorithm to solve this problem and determine its efficiency. . Design a presorting-based algorithm for solving this problem and determine its efficiency. Design a presorting-based algorithm for solving this problem and determine its efficiency