6. Consider the following function: (4pts) F = 2, Fr = (Fn-) n > 2 (a) What is the complexity of the algorithm that computes F, using the recursive definition given above. (b) Describe a more efficient algorithm to calculate F, and give its running time. 7. Exercise 4.45 page 180 Two binary trees are similar if they are both empty or both nonempty and have similar left and right subtrees. (a) Write a function to decide whether two binary trees are similar. (b) What is the running time of your function ? (4pts)