Implement a stack using a Queue

Question

Shriram · Accepted Answer

I think you meant "Implement a queue using stack"

Yo · Answer

Use 2 queues: queue1 and queue2:

public void push(E e) {
  queue1.enqueue(e);
}

public E pop() {
  while( queue1.size() > 1) {
       queue2.enqueue( queue1.dequeue() );
  }
  E e = queue1.dequeue();
  swapQueues( queue1, queue2 );
  return e;
  }

Utilisateur anonyme · Answer

Push: enque the new element E, dequeue all existing elements (except for E) and enqueue them again.
Pop: dequeue.

Utilisateur anonyme · Answer

Use two stacks , one for enqueuing, another one for dequeuing. 

function enqueue(){
   if (stack1.length !== 0){
      while (stack2.length !== 0){
          stack1.push(stack2.pop());
      }
   }
   return stack1.pop();
}

function dequeue(){
   if (stack2.length !== 0){
        while(stack1.length !== 0){
            stack2.push(stack1.pop());
        }
   }
   return stack2.pop();
}

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