package main

import (
	"fmt"
	"os"
)

type Node struct {
	val int
	pNode *Node
}

type Stack struct {
	pTop,pBottom *Node
}

func initStack(pStack *Stack){
	pNew:=new(Node)
	pNew.pNode=nil
	pStack.pTop=pNew
	pStack.pBottom=pNew
	if pStack.pTop==nil || pStack.pBottom==nil {
		fmt.Println("分配頭節點記憶體失敗，程式退出")
		os.Exit(-1)
	}
}

func push(pStack *Stack,val int) {
	pNew:=new(Node)
	pNew.val=val
	if pNew==nil {
		fmt.Println("分配頭節點記憶體失敗，程式退出")
		os.Exit(-1)
	}
	pNew.pNode=pStack.pTop
	pStack.pTop=pNew
}

func pop(pStack *Stack)(bool ,int) {
	if isempty(pStack) {
		return false,0
	}
	reval:=pStack.pTop.val
	pStack.pTop=pStack.pTop.pNode
	return true,reval
}
func isempty(pStack *Stack)bool {
	if pStack.pTop==pStack.pBottom{
		return true
	}
	return false
}
func traverse(pStack *Stack){
	if isempty(pStack) {
		return
	}
	p:=pStack.pTop
	for ;p!=pStack.pBottom;p=p.pNode {
		fmt.Printf("%d ",p.val)
	}
	fmt.Println()
}

func clear(pStack *Stack){
	if isempty(pStack) {
		return
	}
	pStack.pTop=pStack.pBottom
}
func main() {
        var pstack Stack
	initStack(&pstack)

	rebool,reval:=pop(&pstack)
	if rebool {
		fmt.Printf("出棧成功，出棧值為：%d\n",reval)
	} else {
		fmt.Println("出棧出錯")
	}
	traverse(&pstack)
	clear(&pstack)
	traverse(&pstack)
}