Hash Functions
  - what's the point
  - tell good from bad, what makes the difference
  - how to test, poisson but don't need to remember formula
Hash Tables
  - how the implementation works, add, find
  - dealing with hash collisions
  - closed addressing = open hashing = e.g. linked lists
  - open addressing = closed hashing = e.g. linear probing
  - resizing - why, when, and how
Binary Files
  - fopen, fgetc, fputc, fclose
  - readsome, read, write, tellg, tellp, seekg, seekp, (gcount)
Graphs
  - construction and linking of nodes
  - depth-first (tree like) search
  - breadth first (queue) search
  - stacks and queues
  - shortest path
Priority Queues
  - as abstract data type
  - implementations
Heaps
  - adding and fix_upwards
  - removing top and fix_downwards
  - heapsort