We use cookies to ensure you have the best browsing experience on our website. Please read our cookie policy for more information about how we use cookies.
  1. Queues: A Tale of Two Stacks
  2. Discussions

Queues: A Tale of Two Stacks

  • WittyNotes
     + 19 comments

    I went down the wrong path at first: transferring data between stacks for every operation. Then I realized that in theory, we never needed to transfer from the 'old' stack to the 'new' stack.

            public void enqueue(T value) { // Push onto newest stack
            stackNewestOnTop.push(value);
        }

        public T peek() {
             prepOld();
             return stackOldestOnTop.peek();
        }

        public T dequeue() {
            
            prepOld();
            return stackOldestOnTop.pop();
            
        }
        
        public void prepOld(){
            if (stackOldestOnTop.isEmpty())
                while(!stackNewestOnTop.isEmpty())
                    stackOldestOnTop.push(stackNewestOnTop.pop());
        }