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.

- 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

• 1 <= x <= 9
• At most 100 calls will be made to push, pop, peek, and empty.
• All the calls to pop and peek are valid.

使用 slice 實現 queue 並 implement queue basic operations:

• push(x)
• pop()
• peek()
• empty()

type MyQueue struct {
	queue []int
}

func Constructor() MyQueue {
	return MyQueue{queue: make([]int, 0)}
}

func (this *MyQueue) Push(x int) {
	this.queue = append(this.queue, x)
}

func (this *MyQueue) Pop() int {
	head := this.queue[0]
	this.queue = this.queue[1:]
	return head
}

func (this *MyQueue) Peek() int {
	return this.queue[0]
}

func (this *MyQueue) Empty() bool {
	return len(this.queue) == 0
}

• Time complexity: O(1)

  • Each operation is amortized O(1) time complexity
  • Runtime: 0 ms, faster than 100.00% of Go online submissions for Implement Queue using Stacks.

• Space complexity: O(n)

  • Where n is the number of push operations.
  • Memory Usage: 1.9 MB, less than 85.17% of Go online submissions for Implement Queue using Stacks.