Asymptotic Complexity. Java. Did I solve the test problem correctly?

Question

Java

Hello! I am doing a test task for training, who can help with the test? Everything about Asymptotic Complexity. Java language.
Determine the asymptotic complexity of the following algorithm:
int[] array = new int[n];
for (int i = 0; i <= array.length - 2; i += 2) {
array[i] = i;
}
Answer O( n/2 )
Using O-notation, indicate, separated by commas, the asymptotic complexity of the following algorithms: a) Key lookup in a hash table
b) Arbitrary index access in an array
c) Arbitrary index access in a singly linked list
d) Access by an arbitrary index in a doubly linked list f) Quick sort (quick sort) g) Search in a balanced tree Answer
e) Deletion at an arbitrary index in a singly linked list
a) O(1) b) O(1) c) O(N) d) O(N) e) O(1) f) O(n log(n)) g) O(log n)

Answer 1

You don't fully understand what asymptotic complexity is. "Answer O( n/2 )" is fundamentally wrong, because O implies any constant factor. Even if there was a cycle from 1 to n*100..billion..zeros..00, the complexity would still be O(n).
e) wrong. In order to remove an arbitrary element of a linked list, you must first find it.
f) false, q-sort without modification can degenerate to O(n^2). O(n log n) on average.
The rest is correct.