# *Square fence* You're given an array L which represents the lengths of n planks. You have to answer if there's any way to form the edges of a square fence using all the planks without breaking or overlapping them.  (Hint: complexity $O(4^n/2^)$)
# *8 puzzle* The 8 puzzle is a sliding tile game of 3x3 slots with 8 tiles and one empty slot. At each step you can move one of the orthogonally neighbouring tiles to the empty slot. The game starts from a random initial configuration and the purpose is to get to the final sorted configuration in the fewest number of moves. Figure out an efficient algorithm that solves the 8 puzzle. (Hint: Each position is solvable in at most 31 moves) In the picture we see a sequence of moves that solves the puzzle.
!blog/meet-in-the-middle?8puzzle.png!

# *4 reversals* We are given two equal length strings S and T. Figure out if we can get string T starting from string S and applying 4 substring reversal operations. (Hint: complexity O(n^5^))

# *4 reversals* We are given two equal length strings S and T. Figure out if we can get string T starting from string S and applying 4 reversal operations. (Hint: complexity O(n^5^))

The additional problems are the best part of the article so try to solve them in the comment section.