Question

Page ot 9 2. Stacks/Queues: Write a method splitStack that takes a stack of integers as a parameter and splits it into negatives and non-negatives. The numbers in the stack should be rearranged so that all the negatives appear on the bottom of the stack and all the non-negatives appear on the top. In other words, if after this method is called you were to pop numbers off the stack, you would first get all the nonnegative numbers and then get all the negative numbers. It does not matter what order the numbers appear in as long as all the negatives appear lower in the stack than all the non-negatives. You may use a single queue as auxiliary storage. For example, if the stack stores [3, -5, 1, 2,-4], an acceptable result would be [-5, -4, 3, 1, 2

Answer 1

Here is the completed code for this method. Assuming the language is Java. Please don’t forget to mention the language while you post a question in future. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. Thanks

//required method, using Stack & Queue from java.util library

static void splitStack(Stack<Integer> stk) {

      // creating a queue as auxiliary storage

      Queue<Integer> auxQueue = new LinkedList<Integer>();

      // moving each value from stk to the queue

      while (!stk.isEmpty()) {

            auxQueue.add(stk.pop());

      }

      // finding the size of the queue

      int size = auxQueue.size();

      // looping for size number of times

      for (int i = 0; i < size; i++) {

            // removing front element from queue

            int number = auxQueue.remove();

            // if number is negative, pushing to stack

            if (number < 0) {

                  stk.push(number);

            } else {

                  // otherwise adding to the end of queue

                  auxQueue.add(number);

            }

      }

      // at this point, the stack will only contain negative values, all

      // positive values are left on the queue, so we just simply add them to

      // the stack, so that positive values will be at the top

     

      // looping and removing each value remaining on the queue into the stack

      while (!auxQueue.isEmpty()) {

            stk.push(auxQueue.remove());

      }

}