implementQueueusingStacks.js

////////////////////////////////////////////////Implement Queue using Stacks/////////////////////////////////////////////
// Implement a first in first out (FIFO) queue using only two stacks. The implemented queue should support all the functions
// of a normal queue (push, peek, pop, and empty).
// Implement the MyQueue class:
// void push(int x) Pushes element x to the back of the queue.
// int pop() Removes the element from the front of the queue and returns it.
// int peek() Returns the element at the front of the queue.
// boolean empty() Returns true if the queue is empty, false otherwise.
// Notes:
// You must use only standard operations of a stack, which means only push to top, peek/pop from top, size, and is empty operations are valid.
// Depending on your language, the stack may not be supported natively. You may simulate a stack using a list or deque
// (double-ended queue) as long as you use only a stack's standard operations.
// Example 1:
// Input
// ["MyQueue", "push", "push", "peek", "pop", "empty"]
// [[], [1], [2], [], [], []]
// Output
// [null, null, null, 1, 1, false]
// Explanation
// MyQueue myQueue = new MyQueue();
// myQueue.push(1); // queue is: [1]
// myQueue.push(2); // queue is: [1, 2] (leftmost is front of the queue)
// myQueue.peek(); // return 1
// myQueue.pop(); // return 1, queue is [2]
// myQueue.empty(); // return false
const MyQueue = function() {
    this.stack = [];
    this.stack2 = [];
};

/**
 * @param {number} x
 * @return {void}
 */
MyQueue.prototype.push = function(x) {
    this.stack.push(x)
};

/**
 * @return {number}
 */
MyQueue.prototype.pop = function() {
    while (this.stack.length) {
        this.stack2.push(this.stack.pop())
    }
    let p = this.stack2.pop()
    while (this.stack2.length) {
        this.stack.push(this.stack2.pop())
    }
    return p;
};

/**
 * @return {number}
 */
MyQueue.prototype.peek = function() {
    return this.stack[0];
};

/**
 * @return {boolean}
 */
MyQueue.prototype.empty = function() {
    return (this.stack.length || this.stack2.length) ? false : true;
};

/**
 * Your MyQueue object will be instantiated and called as such:
 * var obj = new MyQueue()
 * obj.push(x)
 * var param_2 = obj.pop()
 * var param_3 = obj.peek()
 * var param_4 = obj.empty()
 */