Implement Stack Using Queue

Problem

Implement the following operations of a stack using queues.

push(x) -- Push element x onto stack. pop() -- Removes the element on top of the stack. top() -- Get the top element. empty() -- Return whether the stack is empty. Notes: You must use only standard operations of a queue -- which means only push to back, peek/pop from front, size, and is empty operations are valid. Depending on your language, queue may not be supported natively. You may simulate a queue by using a list or deque (double-ended queue), as long as you use only standard operations of a queue. You may assume that all operations are valid (for example, no pop or top operations will be called on an empty stack).

Solution

One Queue Solution

class MyStack {

    Queue<Integer> q;
    /** Initialize your data structure here. */
    public MyStack() {
        this.q = new LinkedList<>();
    }

    /** Push element x onto stack. */
    public void push(int x) {
        q.offer(x);
        int size = q.size();
        while (size-- > 1) q.offer(q.remove()); //Move all the elements before to last added to its behind 

    }

    /** Removes the element on top of the stack and returns that element. */
    public int pop() {
        return q.remove();
    }

    /** Get the top element. */
    public int top() {
        return q.peek();
    }

    /** Returns whether the stack is empty. */
    public boolean empty() {
        return q.isEmpty();
    }
}

/**
 * Your MyStack object will be instantiated and called as such:
 * MyStack obj = new MyStack();
 * obj.push(x);
 * int param_2 = obj.pop();
 * int param_3 = obj.top();
 * boolean param_4 = obj.empty();
 */

Analysis

We use one queue by manipulating the stack.push() method in queue
All other methods are exact same in stack