1.先序遍历非递归算法
void PreOrderUnrec(Bitree *t) { Stack s; StackInit(s); Bitree *p=t; while (p!=NULL || !StackEmpty(s)) { while (p!=NULL) //遍历左子树 { visite(p->data); push(s,p); p=p->lchild; } 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 }

2.中序遍历非递归算法
void InOrderUnrec(Bitree *t) { Stack s; StackInit(s); Bitree *p=t; while (p!=NULL || !StackEmpty(s)) { while (p!=NULL) //遍历左子树 { push(s,p); p=p->lchild; } 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 }

3.后序遍历非递归算法
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

二、前序最简洁算法
void PreOrderUnrec(Bitree *t) { Bitree *p; Stack s; s.push(t); while (!s.IsEmpty()) { s.pop(p); visit(p->data); if (p->rchild != NULL) s.push(p->rchild); if (p->lchild != NULL) s.push(p->lchild); } }

三、后序算法之二
void BT_PostOrderNoRec(pTreeT root) { stack<treeT *> s; pTreeT pre=NULL; while ((NULL != root) || !s.empty()) { if (NULL != root) { s.push(root); root = root->left; } else { root = s.top(); if (root->right!=NULL && pre!=root->right){ root=root->right; } else{ root=pre=s.top(); visit(root); s.pop(); root=NULL; } } } }