How many distinct BSTs can be constructed with 3 distinct keys?

You are given the postorder traversal, P, of a binary search tree on the n elements 1, 2,..........., n. You have to determine the unique binary search tree that has P as its postorder traversal. What is the time complexity of the most efficient algorithm for doing this?

Consider the following sequence of nodes for the undirected graph given below.
1.a b e f d g c
2.a b e f c g d
3.a d g e b c f
4.a d b c g e f
A Depth First Search (DFS) is started at node a. The nodes are listed in the order they are first visited. Which all of the above is (are) possible output(s)?

Consider a hash table of size 11 that uses open addressing with linear probing. Let h(k) = k mod 11 be the hash function used. A sequence of records with keys

43 36 92 87 11 4 71 13 14 is inserted into an initially empty hash table, the bins of which are indexed from zero to ten. What is the index of the bin into which the last record is inserted?