Developing Algorithms Using ArrayLists

AP Computer Science A· difficulty 4/5

ArrayList<Integer> list = new ArrayList<>();
list.add(2);
list.add(2);
list.add(2);
list.add(2);
for (int i = 0; i < list.size(); i++) {
    if (list.get(i) == 2) list.remove(i);
}
System.out.println(list);

What is printed?

A
$[]$
B
$[2, 2, 2, 2]$
C
$[2, 2]$
check_circle
D
$[2]$

Explanation

This is the classic remove-while-iterating bug. After removing index 0, elements shift left, so i increments past the next 2. Indices visited: 0 (remove), 1 was originally index 2 (remove), leaving two 2s untouched.

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