#include<stdio.h>
#include<stdlib.h>

typedef struct nodf     //树的结点结构体
{
    int data;
    struct nodf *lchild,*rchild;
}bitree;
bitree *Q[20];//定义一个指向bitree的指针数组

typedef struct node
{
    bitree *s;
    struct node *next;
}linkstack;
linkstack *top=NULL;//空栈


linkstack *push(linkstack *top,bitree *x)//进栈
{
    linkstack *p;
    p=(linkstack*)malloc(sizeof(linkstack));
    p->s=x;
    p->next=top;
    top=p;
    return top;
}

linkstack *pop(linkstack *top)//出栈
{
    linkstack *p;
    p=top;
    top=top->next;
    free(p);
    return top;
}

int empty(linkstack *s)
{
    if(s->next==NULL)
    return 1;
    else
    return 0;
}

bitree *creatree()
{
    int ch;
    int front=1,rear=0;
    bitree *root,*s;
    root=NULL;
    scanf("%d",&ch);
    while(ch!=-1)
    {
        s=NULL;
        if(ch!=0)
        {
            s=(bitree*)malloc(sizeof(bitree));
            s->data=ch;
            s->lchild=NULL;
            s->rchild=NULL;
        }
        rear++;
        Q[rear]=s;
        if(rear==1)  root=s;
        else
        {
            if(s!=NULL&&Q[front]!=NULL)
            {
                if(rear%2==0)  Q[front]->lchild=s;
                else           Q[front]->rchild=s;
                if(rear%2==1)  front++;
            }
        }
        scanf("%d",&ch);
    }
    return root;
}


void pri(bitree *s,linkstack *top)//先序排列 非递归
{
    linkstack *acc;
    while(s!=NULL||(empty(top)==0))
    {
        while(s!=NULL)
        {
            printf("%d ",s->data);
                top=push(top,s);
                s=s->lchild;
        }
        if(s==NULL)
        {
            acc=pop(top);                //这里的出栈并不能使free里的实参回收，导致不断地循环  可是我想不出应该怎么去修改
            s=acc->s->rchild;
        }
    }
}

int main()
{
    bitree *tree=creatree();
    pri(tree,top);
    return 0;
}
 

这个答案好像不太好咧···