數據結構的C實現_二叉樹

//編譯環境 visual studio 2008，win32 console application.

//BiTree.c

//二叉樹及其遞歸和非遞歸遍歷
#include <stdlib.h>
#include <stdio.h>
#define MAXKEY 100
#define OK 1

typedef char elemType;

typedef struct _node
{
elemType key;
struct _node *lchild;
struct _node *rchild;
}Node;//二叉樹節點



//遞歸先序遍歷
void PreOrder_R(Node *tree)
{
if(tree!=NULL)
{
printf(" %c",tree->key);
PreOrder_R(tree->lchild);
PreOrder_R(tree->rchild);
}
}

//遞歸中序遍歷
void InOrder_R(Node *tree)
{
if(tree!=NULL)
{
InOrder_R(tree->lchild);
printf(" %c",tree->key);
InOrder_R(tree->rchild);
}
}

//遞歸後序遍歷
void PostOrder_R(Node *tree)
{
if(tree!=NULL)
{
PostOrder_R(tree->lchild);
PostOrder_R(tree->rchild);
printf(" %c",tree->key);
}
}

//非遞歸先序遍歷
void PreOrder_NR(Node *tree)
{
Node *stack[100];
int top=0;
Node *p=tree;
while(p!=NULL||top>0)
{
while(p!=NULL)
{
printf(" %c",p->key);
stack[top++]=p;//根節點入棧
p=p->lchild;
}
p=stack[--top];
p=p->rchild;
}
}
//非遞歸中序遍歷
void InOrder_NR(Node *tree)
{
Node *stack[100];
int top=0;
Node *p=tree;
while(p!=NULL||top>0)
{
while(p!=NULL)
{
stack[top++]=p;
p=p->lchild;
}//左孩子入棧
p=stack[--top];
printf(" %c",p->key);
p=p->rchild;
}
}

//非遞歸後序遍歷
void PostOrder_NR(Node *tree)
{
Node *stack[100];
int top=0;
Node *p=tree;
Node *lastvisit=NULL;
while(p!=NULL||top>0)
{
while(p!=NULL)
{
stack[top++]=p;
p=p->lchild;
}//左孩子入棧
p=stack[top-1];
if(p->rchild==NULL||p->rchild==lastvisit)
{
printf(" %c",p->key);
--top;
lastvisit=p;
p=NULL;
}//訪問中間節點
else
p=p->rchild;
}
}

//清空樹
int DeleteTree(Node *tree)
{
if(tree!=NULL)
{
DeleteTree(tree->lchild);
DeleteTree(tree->rchild);
free(tree);
}
return OK;
}

main()
{
//創建一個二叉樹
Node *tree,*p;
p=malloc(sizeof(Node));
p->key='A';
tree=p;

p=malloc(sizeof(Node));
p->key='B';
tree->lchild=p;

p=malloc(sizeof(Node));
p->key='C';
p->lchild=NULL;
p->rchild=NULL;
tree->lchild->lchild=p;

p=malloc(sizeof(Node));
p->key='D';
p->lchild=NULL;
p->rchild=NULL;
tree->lchild->rchild=p;

p=malloc(sizeof(Node));
p->key='E';
p->lchild=NULL;
tree->rchild=p;

p=malloc(sizeof(Node));
p->key='F';
p->lchild=NULL;
p->rchild=NULL;
tree->rchild->rchild=p;

printf("遞歸先序遍歷:\n");
PreOrder_R(tree);

printf("\n非遞歸先序遍歷:\n");
PreOrder_NR(tree);

printf("\n遞歸中序遍歷:\n");
InOrder_R(tree);

printf("\n非遞歸中序遍歷:\n");
InOrder_NR(tree);

printf("\n遞歸後序遍歷:\n");
PostOrder_R(tree);

printf("\n非遞歸後序遍歷:\n");
PostOrder_NR(tree);
printf("\n");
DeleteTree(tree);
}