[转]二叉树三种遍历的非递归算法转

1.先序遍历非递归算法
#define maxsize 100typedef 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 100typedef 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 100typedef 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