Leetcode-implement Queue using Stacks

Implement the following operations of a queue using stacks.

• Push (x)--push element x to the back of the queue.
• Pop ()--Removes the element from in front of the queue.
• Peek ()--Get the front element.
• Empty ()--Return whether the queue is empty.

Notes:

• you must Use only  standard operations of a stack--which means only < Code style= "Font-family:menlo,monaco,consolas, ' Courier New ', monospace; font-size:12.6000003814697px; PADDING:2PX 4px; Color:rgb (199,37,78); Background-color:rgb (249,242,244) ">push to top ,  peek/pop from top ,  size , And is empty  operations is valid.
• Depending on your language, stack may is not supported natively. You could simulate a stack by using a list or deque (double-ended queue), as long as if you have standard operations of a s Tack.
• You may assume this all operations is valid (for example, no pop or peek operations would be called on an empty queue).

This problem can run a few examples of their own first will find that there are rules to follow, the main idea is two stacks, a stack1 for push, and another stack2 for pop, the key is in the process from Stack1 to Stack2, or directly on the code bar, at a glance:

Class Myqueue {        linkedlist<integer> stack1 = new linkedlist<integer> ();    linkedlist<integer> Stack2 = new linkedlist<integer> ();        Push element x to the back of the queue.    public void push (int x) {        stack1.push (x);    }    Removes the element from in front of the queue.    public void POPs () {       if (Stack2.isempty ()) {           while (!stack1.isempty ()) {               Stack2.push (Stack1.pop ())           };}       }       Stack2.pop ();    }    Get the front element.    public int Peek () {    if (Stack2.isempty ()) {           while (!stack1.isempty ()) {               Stack2.push (Stack1.pop ());           }       }       return Stack2.peek ();    }    Return whether the queue is empty.    public Boolean empty () {        return stack1.isempty () && stack2.isempty ();}    }

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Leetcode-implement Queue using Stacks