《数据结构》——二叉树先中后三种遍历方式相关代码整理

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

typedef struct BTNode
{
    int data;
    struct BTNode * pLchild;
    struct BTNode * pRchild;
}BTNODE,*PBTNODE;

PBTNODE CreateBTree(void);
void PreTraverseBTree(PBTNODE PT);
void InTraverseBTree(PBTNODE PT);
void PostTraverseBTree(PBTNODE PT);

int main(void)
{
    PBTNODE pT=CreateBTree();
//    PreTraverseBTree(pT);
//    InTraverseBTree(pT);
    PostTraverseBTree(pT);
    return 0;
}

PBTNODE CreateBTree(void)
{
    PBTNODE PA=(PBTNODE)malloc(sizeof(BTNODE));
    PBTNODE PB=(PBTNODE)malloc(sizeof(BTNODE));
    PBTNODE PC=(PBTNODE)malloc(sizeof(BTNODE));
    PBTNODE PD=(PBTNODE)malloc(sizeof(BTNODE));
    PBTNODE PE=(PBTNODE)malloc(sizeof(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;
}

//先序遍历
void PreTraverseBTree(PBTNODE PT)
{
    if(NULL != PT)
    {
        printf("%c\n",PT->data);
        if(NULL != PT->pLchild)
        {
            PreTraverseBTree(PT->pLchild);
        }
        if(NULL != PT->pRchild)
        {
            PreTraverseBTree(PT->pRchild);
        }
    }
}

//中序遍历
void InTraverseBTree(PBTNODE PT)
{
    if(NULL != PT)
    {

        if(NULL != PT->pLchild)
        {
            InTraverseBTree(PT->pLchild);
        }
        printf("%c\n",PT->data);
        if(NULL != PT->pRchild)
        {
            InTraverseBTree(PT->pRchild);
        }
    }
}

//后序遍历
void PostTraverseBTree(PBTNODE PT)
{
    if(NULL != PT)
    {

        if(NULL != PT->pLchild)
        {
            PostTraverseBTree(PT->pLchild);
        }
        if(NULL != PT->pRchild)
        {
            PostTraverseBTree(PT->pRchild);
        }
            printf("%c\n",PT->data);
    }
}