第十周项目4-二叉树遍历的非递归算法

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btree.h

#ifndef BTREE_H_INCLUDED#define BTREE_H_INCLUDED#define MaxSize 100typedef char ElemType;typedef struct node{    ElemType data;              //数据元素    struct node *lchild;        //指向左孩子    struct node *rchild;        //指向右孩子} BTNode;void CreateBTNode(BTNode *&b,char *str);        //由str串创建二叉链BTNode *FindNode(BTNode *b,ElemType x);     //返回data域为x的节点指针BTNode *LchildNode(BTNode *p);  //返回*p节点的左孩子节点指针BTNode *RchildNode(BTNode *p);  //返回*p节点的右孩子节点指针int BTNodeDepth(BTNode *b); //求二叉树b的深度void DispBTNode(BTNode *b); //以括号表示法输出二叉树void DestroyBTNode(BTNode *&b);  //销毁二叉树#endif // BTREE_H_INCLUDED

btree.cpp

#include <stdio.h>#include <malloc.h>#include "btree.h"void CreateBTNode(BTNode *&b,char *str)     //由str串创建二叉链{    BTNode *St[MaxSize],*p=NULL;    int top=-1,k,j=0;    char ch;    b=NULL;             //建立的二叉树初始时为空    ch=str[j];    while (ch!='\0')    //str未扫描完时循环    {        switch(ch)        {        case '(':            top++;            St[top]=p;            k=1;            break;      //为左节点        case ')':            top--;            break;        case ',':            k=2;            break;                          //为右节点        default:            p=(BTNode *)malloc(sizeof(BTNode));            p->data=ch;            p->lchild=p->rchild=NULL;            if (b==NULL)                    //p指向二叉树的根节点                b=p;            else                            //已建立二叉树根节点            {                switch(k)                {                case 1:                    St[top]->lchild=p;                    break;                case 2:                    St[top]->rchild=p;                    break;                }            }        }        j++;        ch=str[j];    }}BTNode *FindNode(BTNode *b,ElemType x)  //返回data域为x的节点指针{    BTNode *p;    if (b==NULL)        return NULL;    else if (b->data==x)        return b;    else    {        p=FindNode(b->lchild,x);        if (p!=NULL)            return p;        else            return FindNode(b->rchild,x);    }}BTNode *LchildNode(BTNode *p)   //返回*p节点的左孩子节点指针{    return p->lchild;}BTNode *RchildNode(BTNode *p)   //返回*p节点的右孩子节点指针{    return p->rchild;}int BTNodeDepth(BTNode *b)  //求二叉树b的深度{    int lchilddep,rchilddep;    if (b==NULL)        return(0);                          //空树的高度为0    else    {        lchilddep=BTNodeDepth(b->lchild);   //求左子树的高度为lchilddep        rchilddep=BTNodeDepth(b->rchild);   //求右子树的高度为rchilddep        return (lchilddep>rchilddep)? (lchilddep+1):(rchilddep+1);    }}void DispBTNode(BTNode *b)  //以括号表示法输出二叉树{    if (b!=NULL)    {        printf("%c",b->data);        if (b->lchild!=NULL || b->rchild!=NULL)        {            printf("(");            DispBTNode(b->lchild);            if (b->rchild!=NULL) printf(",");            DispBTNode(b->rchild);            printf(")");        }    }}void DestroyBTNode(BTNode *&b)   //销毁二叉树{    if (b!=NULL)    {        DestroyBTNode(b->lchild);        DestroyBTNode(b->rchild);        free(b);    }}

main.cpp

#include <stdio.h>#include "btree.h"void PreOrder1(BTNode *b){    BTNode *St[MaxSize],*p;    int top=-1;    if (b!=NULL)    {        top++;                      //根节点入栈        St[top]=b;        while (top>-1)              //栈不为空时循环        {            p=St[top];              //退栈并访问该节点            top--;            printf("%c ",p->data);            if (p->rchild!=NULL)    //右孩子入栈            {                top++;                St[top]=p->rchild;            }            if (p->lchild!=NULL)    //左孩子入栈            {                top++;                St[top]=p->lchild;            }        }        printf("\n");    }}void InOrder1(BTNode *b){    BTNode *St[MaxSize],*p;    int top=-1;    if (b!=NULL)    {        p=b;        while (top>-1 || p!=NULL)        {            while (p!=NULL)            {                top++;                St[top]=p;                p=p->lchild;            }            if (top>-1)            {                p=St[top];                top--;                printf("%c ",p->data);                p=p->rchild;            }        }        printf("\n");    }}void PostOrder1(BTNode *b){    BTNode *St[MaxSize];    BTNode *p;    int flag,top=-1;                        //栈指针置初值    if (b!=NULL)    {        do        {            while (b!=NULL)                 //将t的所有左节点入栈            {                top++;                St[top]=b;                b=b->lchild;            }            p=NULL;                         //p指向当前节点的前一个已访问的节点            flag=1;            while (top!=-1 && flag)            {                b=St[top];                  //取出当前的栈顶元素                if (b->rchild==p)           //右子树不存在或已被访问,访问之                {                    printf("%c ",b->data);  //访问*b节点                    top--;                    p=b;                    //p指向则被访问的节点                }                else                {                    b=b->rchild;            //t指向右子树                    flag=0;                }            }        }        while (top!=-1);        printf("\n");    }}int main(){    BTNode *b;    CreateBTNode(b,"A(B(D,E(H(J,K(L,M(,N))))),C(F,G(,I)))");    printf("二叉树b: ");    DispBTNode(b);    printf("\n");    printf("先序遍历序列:\n");    PreOrder1(b);    printf("中序遍历序列:\n");    InOrder1(b);    printf("后序遍历序列:\n");    PostOrder1(b);    DestroyBTNode(b);    return 0;}

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