# include <stdio.h>
# include <malloc.h>


struct BTNode
{
char data;
struct BTNode * pLchild; //p是指针 L是左  child是孩子
struct BTNode * pRchild;
};


void PostTraverseBTree(struct BTNode * pT);
struct BTNode * CreateBTree(void);
void PreTraverseBTree(struct BTNode * pT);
void InTraverseBTree(struct BTNode * pT);


int main(void)
{
struct BTNode * pT = CreateBTree();

// PreTraverseBTree(pT);
// InTraverseBTree(pT);
PostTraverseBTree(pT);

return 0;
}


void PostTraverseBTree(struct BTNode * pT)
{
if (NULL != pT)
{
if (NULL != pT->pLchild)
{
PostTraverseBTree(pT->pLchild);
}
if (NULL != pT->pRchild)
{
PostTraverseBTree(pT->pRchild);
//pT->pLchild可以代表整个左子树
}
printf("%c\n", pT->data);
}
}


void InTraverseBTree(struct BTNode * pT)
{
if (NULL != pT)
{
if (NULL != pT->pLchild)
{
InTraverseBTree(pT->pLchild);
}

printf("%c\n", pT->data);

if (NULL != pT->pRchild)
{
InTraverseBTree(pT->pRchild);
//pT->pLchild可以代表整个左子树
}
}
}


void PreTraverseBTree(struct BTNode * pT)
{
if (NULL != pT)
{
printf("%c\n", pT->data);

if (NULL != pT->pLchild)
{
PreTraverseBTree(pT->pLchild);
}

if (NULL != pT->pRchild)
{
PreTraverseBTree(pT->pRchild);
//pT->pLchild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
*/
}


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;
}