二叉树3种遍历的非递归算法

http://blog.csdn.net/pipisorry/article/details/37353037

c实现：

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); //訪问根结点
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，表示右子树訪问完成，故訪问根结点
}

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

c++实现：

ref:二叉树遍历之非递归算法http://blog.csdn.net/sgbfblog/article/details/7773103

ref:http://siwei1987.blog.51cto.com/430256/118551

from:http://blog.csdn.net/pipisorry/article/details/37353037