Leetcode专题[数组]-232-用栈实现队列

leetcode:
https://leetcode.cn/problems/implement-queue-using-stacks/des...
解题思路：

type MyQueue struct {
    stack []int
    back  []int
}

/** Initialize your data structure here. */
func Constructor() MyQueue {
    return MyQueue{
        stack: make([]int, 0),
        back:  make([]int, 0),
    }
}

/** Push element x to the back of queue. */
func (this *MyQueue) Push(x int) {
    for len(this.back) != 0 {
        val := this.back[len(this.back)-1]
        this.back = this.back[:len(this.back)-1]
        this.stack = append(this.stack, val)
    }
    this.stack = append(this.stack, x)
}

/** Removes the element from in front of queue and returns that element. */
func (this *MyQueue) Pop() int {
    for len(this.stack) != 0 {
        val := this.stack[len(this.stack)-1]
        this.stack = this.stack[:len(this.stack)-1]
        this.back = append(this.back, val)
    }
    if len(this.back) == 0 {
        return 0
    }
    val := this.back[len(this.back)-1]
    this.back = this.back[:len(this.back)-1]
    return val
}

/** Get the front element. */
func (this *MyQueue) Peek() int {
    for len(this.stack) != 0 {
        val := this.stack[len(this.stack)-1]
        this.stack = this.stack[:len(this.stack)-1]
        this.back = append(this.back, val)
    }
    if len(this.back) == 0 {
        return 0
    }
    val := this.back[len(this.back)-1]
    return val
}

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