FRQ Type 3: Array and ArrayList

array and arraylist

Part of: Exam Workshop: FRQ Strategies

What This FRQ Asks The array FRQ gives you a one-dimensional array or an ArrayList and asks you to search it, sum it, find a maximum, or build a new list from it. The rubric rewards a correct traversal and correct index or element handling. Off-by-one errors are the number one point loss here, so bound your loops carefully. Traversing an Array When you only read elements, a for-each loop is clean and avoids index mistakes: Start max at arr[0], not at 0, or an array of all negative numbers would give the wrong answer. When you need the index, use a counted loop with the correct bound i < arr.length: ArrayList Basics An ArrayList uses methods instead of brackets. The four you need are size(), get(i), add(x), and remove(i). When you remove from an ArrayList inside a loop, be careful. After remove(i), every later element shifts left by one, so blindly doing i++ skips the next element. A common fix is to not increment i in the iteration where you removed. Key points: - Bound array loops with i < arr.length and start a max at arr[0]. - Use size, get, add, and remove for an ArrayList. - Removing during a loop shifts indices, so adjust your counter.

Challenge: Find the Maximum