h2. Additional problems

1. (Square) You're given an array L which represents the sizes of n planks. You have to answer if there's any way to form a square using the planks without breaking them of overlapping them.

1. (Equal partition) Given a set A of 40 real numbers, find out if there is any way to split A in two sets such that the sums of their elements are equal. (O(2^n))
2. (minimal vertex cover) Given a graph of n nodes (n <= 30), find out a set with the smallest number of vertices such that each edge in the  graph has at least one node inside the set. (O(3^n/2))