1. hashing
   1. collision
      1. chaining
      2. open addressing
      3. probing
         1. double hashing
         2. quadratic
         3. linear
   2. function
   3. pigeon hole
2. complexity
   1. space
   2. time
      1. undecided
      2. intractible
      3. tractible
   3. bounds
      1. theta
      2. Omega
      3. O
3. pattern
   1. random
   2. reverse
   3. ordered
4. graphs
   1. connectivity
      1. dense
      2. sparse
   2. structure
      1. isomorphic
      2. subgraph
   3. types
      1. complete
      2. simple
      3. undirected
      4. directed
      5. weighted
   4. navigation
      1. dijkstra's
      2. DFS
      3. BFS
      4. kruskal's
   5. representations
      1. matrix
      2. adjacency list
5. counting
   1. rules
      1. inclusion-exclusion
      2. sum
      3. product
   2. tree diagrams
   3. problems
      1. unordered
      2. ordered
      3. no repetition
      4. repetition
      5. permutation
      6. combination
6. trees
   1. traversal
      1. postfix
      2. prefix
      3. infix
   2. types
      1. AVL
      2. Binary
      3. BST
      4. Heap
      5. B+
   3. structure
      1. nearly complete
      2. complete
7. proofs
   1. complexity
   2. correctness
   3. recurrence relation
   4. recursive
   5. induction
   6. loop invariants
8. sorting
   1. style
      1. iterative
      2. recursive
   2. types
      1. heapsort
      2. mergesort
      3. quicksort
      4. selection
      5. insertion
9. structures
   1. types
      1. linked list
      2. priority queue
      3. hash table
      4. stack
      5. trees
   2. operations
      1. find
      2. delete
      3. insert