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// @Title: 用栈实现队列 (Implement Queue using Stacks)
// @Author: 15816537946@163.com
// @Date: 2021-03-05 23:52:30
// @Runtime: 0 ms
// @Memory: 1.9 MB
type MyQueue struct {
	inStack, outStack []int
}

/** Initialize your data structure here. */
func Constructor() MyQueue {
	return MyQueue{}
}

/** Push element x to the back of queue. */
func (this *MyQueue) Push(x int) {
	this.inStack = append(this.inStack, x)
}

func (this *MyQueue) in2out() {
	for len(this.inStack) > 0 {
		this.outStack = append(this.outStack, this.inStack[len(this.inStack)-1])
		this.inStack = this.inStack[:len(this.inStack)-1]
	}
}

/** Removes the element from in front of queue and returns that element. */
func (this *MyQueue) Pop() int {
	if len(this.outStack) == 0 {
		this.in2out()
	}
	x := this.outStack[len(this.outStack)-1]
	this.outStack = this.outStack[:len(this.outStack)-1]
	return x

}

/** Get the front element. */
func (this *MyQueue) Peek() int {
	if len(this.outStack) == 0 {
		this.in2out()
	}
	return this.outStack[len(this.outStack)-1]

}

/** Returns whether the queue is empty. */
func (this *MyQueue) Empty() bool {
	return len(this.inStack) == 0 && len(this.outStack) == 0

}

/**
 * Your MyQueue object will be instantiated and called as such:
 * obj := Constructor();
 * obj.Push(x);
 * param_2 := obj.Pop();
 * param_3 := obj.Peek();
 * param_4 := obj.Empty();
 */