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

struct BTNode
{
    int data;
    struct BTNode * pLchild; // p 是指針   L 是左   child 是孩子
    struct BTNode * pRchild; // 表示右孩子
};

struct BTNode * CreateBTree(void); //靜態創建二叉樹
void PreTraverseBTree(struct BTNode * pT); //先序遍歷
void InTraverseBTree(struct
 
 BTNode * pT); //中序遍歷
void PostTraverseBTree(struct BTNode * pT); //後續遍歷

int main(void)
{
    BTNode pT = CreateBTree(); //這裏不能加 void
    
    PreTraverseBTree(pT); //先序遍歷
    InTraverseBTree(pT); //中序遍歷
    PostTraverseBTree(pT); //後續遍歷
    
    return 0;
}

void PostTraverseBTree(struct BTNode * pT) //
 
後續遍歷
{
    if (pT != NULL)
    {
        if (NULL != pT->pLchild)
        {
            PostTraverseBTree(pT->pLchild); // pT->pLchild可以代表整個左子樹
        }
        if (NULL != pT->pRchild)
        {
            PostTraverseBTree(pT->pRchild);
        }
        
        printf(
 
"%c\n", pT->data);
    } 
}

void InTraverseBTree(struct BTNode * pT) //中序遍歷
{
    if (pT != NULL)
    {
        if (NULL != pT->pLchild)
        {
            InTraverseBTree(pT->pLchild); // pT->pLchild可以代表整個左子樹
        }
        
        printf("%c\n", pT->data);
        
        if (NULL != pT->pRchild)
        {
            InTraverseBTree(pT->pRchild);
        }
    } 
}

void PreTraverseBTree(struct BTNode * pT) //先序遍歷
{
    if (pT != NULL)
    {
        printf("%c\n", pT->data);
        
        if (NULL != pT->pLchild)
        {
            PreTraverseBTree(pT->pLchild); // pT->pLchild可以代表整個左子樹
        }
        
        if (NULL != pT->pRchild)
        {
            PreTraverseBTree(pT->pRchild);
        }
    } // if 判斷不能省略
    
    
/*   //偽算法

    先訪問跟節點
    再先序訪問左子樹
    在先序訪問右子樹
*/
}

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;
}

C_數據結構_鏈式二叉樹