2. (16%) Please propose an algorithm that can find the intersection between two arrays consisting of m and n integers respectively with time complexity better than O(mn) (8%) and analyze its time complexity. (8%)

(b) Consider another sum-of-subsets problem with n = 4, W =13, and w1= 3, w2 = 4, w3 = 5, w4 = 6. Use a similar tree as above, give a strategy to avoid searching every possible traversing route in the tree, and show that it can still get to the correct answer. (10%)