232.implement-queue-using-stacks.go

/*
 * @lc app=leetcode id=232 lang=golang
 *
 * [232] Implement Queue using Stacks
 */
type MyQueue struct {
	stack1 []int
	stack2 []int
}


/** Initialize your data structure here. */
func Constructor() MyQueue {
    return MyQueue{
		stack1:make([]int,0),
		stack2:make([]int,0),//必须有逗号
	}
}


/** Push element x to the back of queue. */
func (this *MyQueue) Push(x int)  {
    this.stack1 = append(this.stack1,x)
}


/** Removes the element from in front of queue and returns that element. */
func (this *MyQueue) Pop() int {
	// 题目要求，不需要考虑为空时的情况
    if len(this.stack2) != 0{
		top := this.stack2[len(this.stack2)-1]
		this.stack2 = this.stack2[:len(this.stack2)-1]
		return top
	}
	for len(this.stack1) != 0{
		top := this.stack1[len(this.stack1)-1]
		this.stack1 = this.stack1[:len(this.stack1)-1]
		this.stack2 = append(this.stack2,top)
	}
	top := this.stack2[len(this.stack2)-1]
	this.stack2 = this.stack2[:len(this.stack2)-1]
	return top
}


/** Get the front element. */
func (this *MyQueue) Peek() int {
	// 不用考虑为空时的情况
    if len(this.stack2) != 0{
		return this.stack2[len(this.stack2)-1]
	}
	for len(this.stack1) != 0{
		top := this.stack1[len(this.stack1)-1]
		this.stack1 = this.stack1[:len(this.stack1)-1]
		this.stack2 = append(this.stack2,top)
	}
	return this.stack2[len(this.stack2)-1]
}


/** Returns whether the queue is empty. */
func (this *MyQueue) Empty() bool {
    return len(this.stack1) == 0 && len(this.stack2) == 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();
 */