(b) Write a recursive function sum(n) to return the summation of the sequence of consecutive integers from 1 to n using any programming language or pseudo- code.(10%)

(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%)