What is the time complexity of pop() operation when the stack is implemented using an array?

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

public ArrayList<Integer> depthFirstTraversal(int[][] adjacency_matrix, int source){//A matrix and a source index is passed in//The traversal will be performed on this matrix and begin from the source index //Stack is created//This stack will be used to process nodes in LIFO order when an unvisited node is foundStack<Integer> stack = new Stack<>();int numNodes = adjacency_matrix.length; //boolean array is created//This array will have a slot for each node//Whenever an unvisited node is visited it's slot in this array will be markedboolean[] visited = new boolean[numNodes]; //This variable will hold the index of the element currently being analyzedint element; //The result of the traversal will be stored in this arraylistArrayList<Integer> traversal = new ArrayList<Integer>(); //Since the source index is passed in it has already been visitedvisited[source] = true; //The source index is added to the queue to continue processing itstack.push(source); while…

Q7 and 9  Please explain your answer