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1. The topic
1. Various traversal processes and traversal algorithm design of binary tree.
(1) Preorder traversal of the binary tree;
(2) Inorder traversal of the binary tree;
(3) Postorder traversal of the binary tree.
2. Implement various binary tree traversal algorithms
The code is as follows (example):
#include<stdio.h>
#include<malloc.h>
#define MaxSize 100
typedef char ElemType;
typedef struct node
{
ElemType data;
struct node *lchild;
struct node *rchild;
}BTNode;
void CreateBTree(BTNode *&b,char *str)
{
BTNode * St[MaxSize],*p;
int top=-1,k,j=0;char ch;
b=NULL;
ch=str[j];
while(ch!='\0')
{
switch(ch)
{
case'(':top++;St[top]=p;k=1;break;
case')':top--;break;
case',':k=2;break;
default:p=(BTNode *)malloc(sizeof(BTNode));
p->data=ch;p->lchild=p->rchild=NULL;
if(b==NULL)
b=p;
else
{
switch(k)
{
case 1:St[top]->lchild=p;break;
case 2:St[top]->rchild=p;break;
}
}
}
j++;ch=str[j];
}
}
void DestroyBTree(BTNode *&b)
{
if(b!=NULL)
{
DestroyBTree(b->lchild);
DestroyBTree(b->rchild);
free(b);
}
}
BTNode *FindNode(BTNode *b,ElemType x)
{
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)
{
return p->lchild;
}
BTNode *RchildNode(BTNode *p)
{
return p->rchild;
}
int BTHeight(BTNode *b)
{
int lchildh,rchildh;
if(b==NULL)return(0);
else
{
lchildh=BTHeight(b->lchild);
rchildh=BTHeight(b->rchild);
return(lchildh>rchildh)?(lchildh+1):(rchildh+1);
}
}
void DispBTree(BTNode *b)
{
if(b!=NULL)
{
printf("%c",b->data);
if(b->lchild!=NULL||b->rchild!=NULL)
{
printf("(");
DispBTree(b->lchild);
if(b->rchild!=NULL)printf(",");
DispBTree(b->rchild);
printf(")");
}
}
}
#include"btree.cpp"
void PreOrder(BTNode *b)
{
if(b!=NULL)
{
printf("%c",b->data);
PreOrder(b->lchild);
PreOrder(b->rchild);
}
}
void PreOrderl(BTNode *b)
{
BTNode *St[MaxSize],*p;
int top = -1;
if(b!=NULL)
{
top++;
St[top]=b;
while(top>-1)
{
p=St[top];
top--;
printf("%c",p->data);
if(p->rchild!=NULL)
{
top++;
St[top]=p->rchild;
}
if(p->lchild!=NULL)
{
top++;
St[top]=p->lchild;
}
}
printf("\n");
}
}
void InOrder(BTNode *b)
{
if(b!=NULL)
{
InOrder(b->lchild);
printf("%c",b->data);
InOrder(b->rchild);
}
}
void InOrderl(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 PostOrder(BTNode *b)
{
if(b!=NULL)
{
PostOrder(b->lchild);
PostOrder(b->rchild);
printf("%c",b->data);
}
}
void PostOrderl(BTNode *b)
{
BTNode *St[MaxSize],*p;
int top = -1;
bool flag;
if(b!=NULL)
{
do
{
while(b!=NULL)
{
top++;
St[top]=p;
b=b->lchild;
}
p=NULL;
flag=true;
while(top!=-1&&flag)
{
b=St[top];
if(b->rchild==p)
{
printf("%c",b->data);
top--;
p=b;
}
else
{
b=b->rchild;
flag=false;
}
}
}while(top!=-1);
printf("\n");
}
}
void TravLevel(BTNode *b)
{
BTNode *Qu[MaxSize];
int front,rear;
front = rear=0;
if(b!=NULL)printf("%c",b->data);
rear++;
Qu[rear]=b;
while(rear!=front)
{
front=(front+1)%MaxSize;
b=Qu[front];
if(b->lchild!=NULL)
{
printf("%c",b->lchild->data);
rear=(rear+1)%MaxSize;
Qu[rear]=b->lchild;
}
if(b->rchild!=NULL)
{
printf("%c",b->rchild->data);
rear=(rear+1)%MaxSize;
Qu[rear]=b->rchild;
}
}
printf("\n");
}
int main()
{
BTNode *b;
CreateBTree(b,"A(B(D,E(H(J,K(L,M(,N))))),C(F,G(,I)))");
printf("二叉树b:");DispBTree(b);printf("\n");
printf("层次遍历序列:");
TravLevel(b);
printf("先序遍历序列:\n");
printf(" 递归算法:");PreOrder(b);printf("\n");
printf(" 非递归算法:");PreOrder(b);printf("\n");
printf("中序遍历序列:\n");
printf(" 递归算法:");InOrder(b);printf("\n");
printf(" 非递归算法:");InOrder(b);printf("\n");
printf("后序遍历序列:\n");
printf(" 递归算法:");PostOrder(b);printf("\n");
printf(" 非递归算法:");PostOrder(b);printf("\n");
DestroyBTree(b);
return 1;
}
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