二叉树中序遍历递归算法

Question

if(T){
if(Visit(T->data))
if(PreOrderTraverse(T->lchild,Visit))
if(PreOrderTraverse(T->rchild,Visit)) return OK;
return ERROR;
}else return OK;
这是前序遍历递归算法主要部分，请问中序递归遍历算法如何编写？其中Visit是对数据元素操作的应用函数

Answer 1

if(T){
if(InOrderTraverse(T->l,Visit))
if(Visit(T->data))
if(InOrderTraverse(T->r,Visit)) return OK;
return ERROR;
}else return OK;
以上就是中序遍历二叉树
这段程序我全有，具体如下：
#include <alloc.h>

#define ERROR 0;
#define FALSE 0;
#define TRUE 1;
#define OK 1;

typedef int ElemType;
typedef int Status;
typedef int KeyType;

#define EQ(a,b) ((a)==(b))
#define LT(a,b) ((a)< (b))
#define LQ(a,b) ((a)<=(b))

typedef struct BinaryTree //定义二叉树
{
ElemType data;
struct BinaryTree *l;
struct BinaryTree *r;
}*BiTree,BiNode;//

BiNode * new()//为新结点开辟空间
{
return( (BiNode *)malloc(sizeof(BiNode)) );
}

CreateSubTree(BiTree *T,ElemType *all,int i)//创建新有子树
{
if ((all[i]==0)||i>16)
{
*T=NULL;
return OK;
}
*T=new();
if(*T==NULL) return ERROR;
(*T)->data=all[i];
CreateSubTree(&((*T)->l),all,2*i);
CreateSubTree(&((*T)->r),all,2*i+1);
}

CreateBiTree(BiTree *T)//创建新结点
{
ElemType all[16]={0,1,2,3,0,0,4,5,0,0,0,0,6,0,0,0,};
CreateSubTree(T,all,1);
}

printelem(ElemType d)//输出
{
printf("%d\n",d);
}

PreOrderTraverse(BiTree T,int (*Visit)(ElemType d))//前序遍历
{
if(T){
if(Visit(T->data))
if(PreOrderTraverse(T->l,Visit))
if(PreOrderTraverse(T->r,Visit)) return OK;
return ERROR;
} else return OK;
}

InOrderTraverse(BiTree T,int (*Visit)(ElemType d))//中序遍历
{
if(T){
if(InOrderTraverse(T->l,Visit))
if(Visit(T->data))
if(InOrderTraverse(T->r,Visit)) return OK;
return ERROR;
}else return OK;
}

Status SearchBST(BiTree T,KeyType key,BiTree f,BiTree *p){

if(!T) {*p=f;return FALSE;}
else if EQ(key,T->data){ *p=T;return TRUE;}
else if LT(key,T->data) SearchBST(T->l,key,T,p);
else SearchBST(T->r,key,T,p);
}

Status InsertBST(BiTree *T,ElemType e){
BiTree p;
BiTree s;
if(!SearchBST(*T,e,NULL,&p)){
s=(BiTree)malloc(sizeof(BiNode));
s->data=e;s->l=s->r=NULL;
if(!p) *T=s;
else if (LT(e,p->data)) p->l=s;
else p->r=s;
return TRUE;
}
else return FALSE;
}

void Delete(BiTree *p){
BiTree q,s;
if(!(*p)->r){
q=(*p);
(*p)=(*p)->l;
free(q);
}
else if(!(*p)->l){
q=(*p);
(*p)=(*p)->r;
free(q);
}
else {

/* q=(*p);
s=(*p)->l;
while(s->r) {q=s; s=s->r;}
(*p)->data=s->data;
if(q!=(*p) ) q->r=s->l;
else q->l=s->l;
free(s);
*/

q=s=(*p)->l;
while(s->r) s=s->r;
s->r=(*p)->r;
free(*p);
(*p)=q;

}
}

Status DeleteBST(BiTree *T,KeyType key){
if (!(*T) )
{return FALSE;}
else{
if ( EQ(key,(*T)->data)) Delete(T);
else if ( LT(key,(*T)->data)) DeleteBST( &((*T)->l), key);
else DeleteBST( &((*T)->r),key);
return TRUE;
}
}

main()
{
BiTree root;
BiTree sroot=NULL;
int i;
int a[10]={45,23,12,3,33, 27,56,90,120,62};
system("cls");
CreateBiTree(&root);
printf("PreOrderTraverse:\n");
PreOrderTraverse(root,printelem);
printf("InOrderTraverse:\n");
InOrderTraverse(root,printelem);
for(i=0;i<10;i++)
InsertBST(&sroot,a[i]);
printf("InOrderTraverse:\n");
InOrderTraverse(sroot,printelem);
for(i=0;i<3;i++)
DeleteBST(&sroot,a[i]);
printf("Now sroot has nodes:\n");
InOrderTraverse(sroot,printelem);
}

Answer 2

把Visit往下移一行就行了。也就是先遍历lchild，再Visit，最后遍历rchild。