Part 4

data-collections

• 4.1

  Arrays

  The largest unit on the exam starts here. Fixed length, zero-indexed, and the two off-by-one errors that account for most lost marks.

  4 min
• 4.2

  ArrayList

  A list that grows, at the cost of boxing — and one removal bug that appears on the exam almost every year.

  3 min
• 4.3

  2-D arrays

  An array of arrays, not a rectangle — and the FRQ that appears on every exam depends on knowing the difference.

  3 min
• 4.4

  Searching and sorting

  Four algorithms the exam expects you to trace by hand, and the one precondition that makes binary search work.

  4 min
• 4.5

  Recursion

  A method that calls itself. The exam tests tracing it by hand far more often than writing it.

  4 min