# 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. (Hint: complexity $O(3^n/2^)$)
# 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. (Hint: complexity $O(4^n/2^)$)
# 8 puzzle: Solve 8 puzzle. (Hint: Each position is solvable in at most 31 moves)

!scratch-meet-in-the-middle?8puzzle!

!scratch-meet-in-the-middle?8puzzle.png!

Try the to solve these problems in the comment section.