Good candidates can arrive at the binary search tree as the right path in a few minutes, and then take 10-15 minutes working through the rest of the problem and the other roadblocks I toss out.

Big-O, Big-Omega, Big-Theta notations, and their meanings. Basic data structures: Heaps, and Binary Search Trees. Algorithm Design Approaches: Divide and Conquer including analysis using recurrences ...

Tour of the most important data structures, fundamental algorithms, and algorithm design techniques: lists, stacks, queues, dynamic arrays, hash tables, heaps, priority queues, disjoint set unions, ...