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}