225. 用队列实现栈
请你仅使用两个队列实现一个后入先出(LIFO)的栈,并支持普通栈的全部四种操作(push、top、pop 和 empty)。
实现 MyStack 类:
注意:
示例:
提示:
两个队列:
type MyStack struct {
s1 []int
s2 []int
}
func Constructor() MyStack {
return MyStack{}
}
func (this *MyStack) Push(x int) {
// push到s1中
this.s1=append(this.s1,x)
}
func (this *MyStack) Pop() int {
// s2作为临时缓存,
for i:=0;i<len(this.s1)-1;i++{
this.s2=append(this.s2,this.s1[i])
}
res := this.s1[len(this.s1)-1]
this.s1,this.s2=this.s2,nil
return res
}
func (this *MyStack) Top() int {
res := this.Pop()
this.s1=append(this.s1,res)
return res
}
func (this *MyStack) Empty() bool {
if len(this.s1)==0 {
return true
}
return false
}
/**
* Your MyStack object will be instantiated and called as such:
* obj := Constructor();
* obj.Push(x);
* param_2 := obj.Pop();
* param_3 := obj.Top();
* param_4 := obj.Empty();
*/
一个队列:
type MyStack struct {
stack []int
}
func Constructor() MyStack {
return MyStack{}
}
func (this *MyStack) Push(x int) {
this.stack=append(this.stack,x)
}
func (this *MyStack) Pop() int {
res := this.stack[len(this.stack)-1]
this.stack=this.stack[:len(this.stack)-1]
return res
}
func (this *MyStack) Top() int {
return this.stack[len(this.stack)-1]
}
func (this *MyStack) Empty() bool {
if len(this.stack)!=0 {
return false
}
return true
}
/**
* Your MyStack object will be instantiated and called as such:
* obj := Constructor();
* obj.Push(x);
* param_2 := obj.Pop();
* param_3 := obj.Top();
* param_4 := obj.Empty();
*/