树与二叉树遍历演示

#include
#include
#define NULL 0

struct BTNode
{
 char data;
 struct BTNode * pLchild;//p是指针，L为左，chlid为孩子
 struct BTNode * pRchild;
};
//struct BTNode * CreateBTree(void);
//void PreTraverseBTree(struct BTNode * pT)
//先序遍历
void PreTraverseBTree(struct BTNode * pT)
{

 if (pT != NULL)
 {
  printf("%c\n",pT->data);
  // PreTraverseBTree(pT->pLchild);
  // PreTraverseBTree(pT->pRchild);
 if(pT->pLchild != NULL )
 {
  PreTraverseBTree(pT->pLchild);
 }
 if(pT->pRchild != NULL )
 {
  PreTraverseBTree(pT->pRchild);
 }
 }
 
 //pT->可以代表整个左子树
 
 /* 伪算法
 先访问根节点
 再先序访问左子树
 再先序访问右子树*/
}
//中序遍历
void InTraerseBTree(struct BTNode * pT)
{
 if (pT != NULL)
 {
 
  // PreTraverseBTree(pT->pLchild);
  // PreTraverseBTree(pT->pRchild);
 if(pT->pLchild != NULL )
 {
  InTraerseBTree(pT->pLchild);
 }
 printf("%c\n",pT->data);

 if(pT->pRchild != NULL )
 {
  InTraerseBTree(pT->pRchild);
 }
 }
 //pT->可以代表整个左子树
 
 /* 伪算法
 访问左子树
 再访问根节点
 再先序访问右子树*/
}
//后序遍历
void PostTraverseBTree(struct BTNode * pT)
{
 if (pT != NULL)
 {
 
  // PreTraverseBTree(pT->pLchild);
  // PreTraverseBTree(pT->pRchild);
 if(pT->pLchild != NULL )
 {
  PostTraverseBTree(pT->pLchild);
 }
 

 if(pT->pRchild != NULL )
 {
  PostTraverseBTree(pT->pRchild);
 }
 printf("%c\n",pT->data);
 }
 //pT->可以代表整个左子树
 
 /* 伪算法
 先访问左子树
 再先序访问右子树
 再先序访问根节点*/
}
struct BTNode * CreateBTree(void)
{
 struct BTNode * pA = (struct BTNode *)malloc(sizeof(struct BTNode));
 struct BTNode * pB = (struct BTNode *)malloc(sizeof(struct BTNode));
 struct BTNode * pC = (struct BTNode *)malloc(sizeof(struct BTNode));
 struct BTNode * pD = (struct BTNode *)malloc(sizeof(struct BTNode));
 struct BTNode * pE = (struct BTNode *)malloc(sizeof(struct BTNode));
 
 pA->data = 'A';
 pB->data = 'B';
 pC->data = 'C';
 pD->data = 'D';
 pE->data = 'E';
 
 pA->pLchild = pB;
 pA->pRchild = pC;
 pB->pLchild = pB->pRchild = NULL;
 pC->pLchild = pD;
 pC->pRchild = NULL;
 pD->pLchild = NULL;
 pD->pRchild = pE;
 pE->pLchild = pE->pRchild = NULL;
 
 return pA;
}
int main(void)
{
 struct BTNode * pT =CreateBTree();
 printf("先序遍历输出:\n");
 PreTraverseBTree(pT);
 printf("中序遍历输出:\n");
 InTraerseBTree(pT);
 printf("后序遍历输出:\n");
 PostTraverseBTree(pT);
 
 return 0;
}