h2. Additional problems

1. Friend of a friend(inteview question): Given two user names in a social network find an easy way to test if one is a friend of a friend of the other.
2. 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))
3. 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))
4. 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. (complexity O(4^n/2))
5. 8 puzzle: Solve 8 puzzle. (Each position is solvable in at most 31 moves.)
6. Pancake puzzle: sort pancakes in optimal number of moves.

# Friend of a friend(inteview question): Given two user names in a social network find an easy way to test if one is a friend of a friend of the other.
# 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))
# 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))
# 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. (complexity O(4^n/2))
# 8 puzzle: Solve 8 puzzle. (Each position is solvable in at most 31 moves.)
# Pancake puzzle: sort pancakes in optimal number of moves.

Try the to solve these problems in the comment section.
http://www.cs.cornell.edu/~wdtseng/icpc/notes/bt3.pdf