[Data structure] a binary tree is traversed in ascending order before non-recursion.

The data structure is recursive. After a deep understanding, write a three-Order Non-recursive version.

 

//测试数据：abd##eg##h##c#f###include <cstdio>#include <iostream>typedef char ElemType;typedef struct Node{    ElemType elem;    struct Node *lchild,*rchild;}Node,*BiTree;typedef struct{    BiTree *base;    BiTree *top;    int stacksize;}SqStack;void InitStack(SqStack &S){    S.base=(BiTree *)malloc(100*sizeof(BiTree));    if(!S.base) exit(0);    S.top=S.base;    S.stacksize=100;}void GetTop(SqStack S,BiTree &e){    if(S.top==S.base)exit(0);    e=*(S.top-1);}void Pop(SqStack &S,BiTree &e){    if(S.top==S.base)exit(0);    e=*--S.top;  //先自减，再取值}void Push(SqStack &S,BiTree e)//严谨的话还应该有if(S.top-S.base>=S.stacksize)的判断，此处略去{    *S.top++=e;//先赋值，再自加}int Empty(SqStack S){    if(S.top==S.base)return 1;    else return 0;}BiTree CreateTree(BiTree &T){    char ch;    ch=getchar();    if(ch==‘#‘)T=NULL;    else    {        T=(BiTree)malloc (sizeof(Node));        T->elem=ch;        T->lchild=(CreateTree(T->lchild));        T->rchild=(CreateTree(T->rchild));    }    return T;}void Middleordertraverse(BiTree T) //中序非递归遍历{    SqStack S;    InitStack(S);    BiTree p=T;    while(p || !Empty(S))    {        if(p)        {            Push(S,p);            p=p->lchild;        }        else        {            Pop(S,p);            printf("%c   \n",p->elem);            p=p->rchild;        }    }}void Firstordertraverse(BiTree T)//先序非递归遍历{    SqStack S;    InitStack(S);    BiTree p=T;    while(p || !Empty(S))    {        while(p)        {            Push(S,p);            printf("%c   \n",p->elem);            p=p->lchild;        }        if(!Empty(S))        {            Pop(S,p);            p=p->rchild;        }    }}void BehindorderTraverse(BiTree T) //后序非递归遍历{    SqStack S;    InitStack(S);    BiTree pre;//设置标志位，标记是否访问过    BiTree p=T;    while(p || !Empty(S))    {        while(p)  //左孩子向下压栈  直到最左下        {            Push(S,p);            p=p->lchild;        }        GetTop(S,p);   //取当前栈顶  即当前节点最左下        if(!p->rchild || p->rchild==pre)//没右孩子或右孩子被遍历过        {            printf("%c   \n",p->elem);            pre=p; //标记此节点已经走过            Pop(S,p);            if( Empty(S))return ;            //p回到其父节点（前面肯定了没左子树，而进入此循环显然没右孩子）            p=NULL;  //不对p左子树遍历        }        else p=p->rchild;    }    return ;}int main(){    //freopen("in.txt","r",stdin);    printf("请给出二叉树的节点序列：  \n");    BiTree T;    CreateTree(T);    printf(" 中序遍历二叉树结果是 ：  \n");    Middleordertraverse(T);    printf(" 先序遍历二叉树结果是 ：  \n");    Firstordertraverse(T);    printf(" 后序遍历二叉树结果是 ：  \n");    BehindorderTraverse(T);    return 0;}

 

[Data structure] a binary tree is traversed in ascending order before non-recursion.