1.先序遍历非递归算法
#define maxsize 100
typedef struct
{
Bitree Elem[maxsize];
int top;
}SqStack;
void PreOrderUnrec(Bitree t)
{
SqStack s;
StackInit(s);
p=t;
while (p!=null || !StackEmpty(s))
{
while (p!=null) //遍历左子树
{
visite(p->data);
push(s,p);
p=p->lchild;
}//endwhile
if (!StackEmpty(s)) //通过下一次循环中的内嵌while实现右子树遍历
{
p=pop(s);
p=p->rchild;
}//endif
}//endwhile
}//PreOrderUnrec
2.中序遍历非递归算法
#define maxsize 100
typedef struct
{
Bitree Elem[maxsize];
int top;
}SqStack;
void InOrderUnrec(Bitree t)
{
SqStack s;
StackInit(s);
p=t;
while (p!=null || !StackEmpty(s))
{
while (p!=null) //遍历左子树
{
push(s,p);
p=p->lchild;
}//endwhile
if (!StackEmpty(s))
{
p=pop(s);
visite(p->data); //访问根结点
p=p->rchild; //通过下一次循环实现右子树遍历
}//endif
}//endwhile
}//InOrderUnrec
3.后序遍历非递归算法
#define maxsize 100
typedef enum{L,R} tagtype;
typedef struct
{
Bitree ptr;
tagtype tag;
}stacknode;
typedef struct
{
stacknode Elem[maxsize];
int top;
}SqStack;
void PostOrderUnrec(Bitree t)
{
SqStack s;
stacknode x;
StackInit(s);
p=t;
do
{
while (p!=null) //遍历左子树
{
x.ptr = p;
x.tag = L; //标记为左子树
push(s,x);
p=p->lchild;
}
while (!StackEmpty(s) && s.Elem[s.top].tag==R)
{
x = pop(s);
p = x.ptr;
visite(p->data); //tag为R，表示右子树访问完毕，故访问根结点
}
if (!StackEmpty(s))
{
s.Elem[s.top].tag =R; //遍历右子树
p=s.Elem[s.top].ptr->rchild;
}
}while (!StackEmpty(s));
}//PostOrderUnrec
==================================================================================
一个完整的前序遍历非递归
*sy32.c*/
#include <stdio.h>
#include <stdlib.h>
typedef char DataType;
typedef struct node{
DataType data;
struct node *lchild,*rchild;
}BinTNode;
typedef BinTNode *BinTree;
int count;
void CreateBinTree(BinTree *T);
void PreorderN(BinTree T);
#define StackSize 10 /*假定预分配的栈空间最多为10*/
typedef BinTree SDataType; /*栈的元素类型设为整型*/
#define Error printf
typedef struct{
SDataType data[StackSize];
int top;
}SeqStack;
void InitStack(SeqStack *S) /*初始栈*/
{ S->top=-1;
}
int StackEmpty(SeqStack *S) /*判栈空*/
{return S->top==-1;
}
int StackFull(SeqStack *S) /*判栈满*/
{return S->top==StackSize-1;
}
void Push(SeqStack *S, SDataType x) /*进栈*/
{if(StackFull(S))
Error("栈已满\n"); /*上溢退出*/
else S->data[++S->top]=x; /*栈顶指针加1后将x进栈*/
}
SDataType Pop(SeqStack *S) /*出栈*/
{if (StackEmpty(S))
Error("Stack underflow"); /*下溢退出*/
else return S->data[S->top--]; /*栈顶指针返回后将栈顶指针减1*/
}
SDataType StackTop(SeqStack *S) /*取栈顶元素*/
{if (StackEmpty(S))
Error("栈已空\n");
return S->data[S->top];
}
main()
{BinTree T;
char ch1,ch2;
printf("\n欢迎进入二叉树操作测试程序，请选择：\n");
ch1='y';
while(ch1=='y' || ch1=='Y')
{printf("\nA-------------------------二叉树建立");
printf("\nB-------------------------先序遍历（非递归）");
printf("\nC-------------------------退出\n");
scanf("\n%c",&ch2);
switch(ch2)
{case 'A':
case 'a':printf("按二叉树带空指针的先序次序输入结点:\n");
CreateBinTree(&T);
printf("二叉树建立成功\n");break;
case 'B':
case 'b':printf("遍历的结果为:\n");
PreorderN(T);break;
case 'C':
case 'c':ch1='n';break;
default:ch1='n';
}
}
}
void CreateBinTree(BinTree *T)
{char ch;
scanf("\n%c",&ch);
if (ch=='0') *T=NULL;
else {*T=(BinTNode*)malloc(sizeof(BinTNode));
(*T)->data=ch;
CreateBinTree(&(*T)->lchild);
CreateBinTree(&(*T)->rchild);
}
}
void PreorderN(BinTree T)
{/*先序遍历二叉树T的非递归算法*/
SeqStack *S;
BinTree p;
InitStack(S);Push(S,T); /*根指针进栈*/
while(!StackEmpty(S))
{while(p=StackTop(S))
{ printf("%3c",p->data); /*访问入栈结点的数据域*/
Push(S,p->lchild); /*向左走到尽头*/
}
p=Pop(S); /*空指针退栈*/
if (!StackEmpty(S)) /*输出结点，向右一步*/
{p=Pop(S);
/* printf("%3c",p->data); */
Push(S,p->rchild);
}
}
}/*PreorderN */
