low-level algorithm and ARM assembly

We have an array. we like to use stack library(Assume it alreay exist and you can use it) to reverse the order of it. Write a method called myRevArray(int[] arr) that would inverse the order of the array with the use of stack you may use the stack library exits and use push and pop from it  do not create a new array as it would be memory wasting  try to have your code in O(n) where n is the size of array [HINT: O(2n) is till O(n)] The method has no return but we use pass by reference to change arr value (you do not need to do anything but by changing the order of arr it automatically will be reverse

Make and implement a mergesort variation that gives an int[] array perm, where perm[i] is the index of the array's i th smallest element, rather than rearranges the array's elements.

Select all explicit instructions that apply to the following prompt:   Implement an open addressing hash table to store a list of integers. Your task is to handle collisions using open addressing and implement basic operations such as insertion, deletion, and searching. The open addressing technique you will use is linear probing.