package java_exercise;

import java.util.Stack;

public class ImplementQueueUsingStacks {

/*

* mplement the following operations of a queue using stacks.

* push(x) -- Push element x to the back of queue.

* pop() -- Removes the element from in front of queue.

* peek() -- Get the front element.

* empty() -- Return whether the queue is empty.

*/

Stack<Integer> converter = new Stack<Integer>();

Stack<Integer> s = new Stack<Integer>();

public void push(int x) {

if (s.empty()) {

s.push(x);

} else {

while(!s.empty()) {

converter.push(s.pop());

}

converter.push(x);

while(!converter.empty()) {

s.push(converter.pop());

}

}

}

// Removes the element from in front of queue.

public void pop() {

s.pop();

}

// Get the front element.

public int peek() {

return s.peek();

}

// Return whether the queue is empty.

public boolean empty() {

return (s.empty());

}

}