[轉]二叉樹三種遍歷的非遞歸算法轉

1.先序遍歷非遞歸算法
#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) //遍歷左子樹 { visite(p->data); push(s,p); p=p->lchild; }//endwhile if (!StackEmpty(s)) //通過下一次循環中的內嵌while實現右子樹遍歷 { p=pop(s); p=p->rchild; }//endif }//endwhile }//PreOrderUnrec

2.中序遍歷非遞歸算法
#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) //遍歷左子樹 { push(s,p); p=p->lchild; }//endwhile if (!StackEmpty(s)) { p=pop(s); visite(p->data); //訪問根結點 p=p->rchild; //通過下一次循環實現右子樹遍歷 }//endif }//endwhile }//InOrderUnrec

3.後序遍歷非遞歸算法
#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) //遍歷左子樹 { x.ptr = p; x.tag = L; //標記爲左子樹 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爲R，表示右子樹訪問完畢，故訪問根結點 } if (!StackEmpty(s)) { s.Elem[s.top].tag =R; //遍歷右子樹 p=s.Elem[s.top].ptr->rchild; } }while (!StackEmpty(s)); }//PostOrderUnrec