二叉树遍历

#include<stdio.h>
#include<malloc.h>
typedef char ElemType;
struct LBinaryTreeNode//二叉树结点
{
    ElemType data;
    struct LBinaryTreeNode * lchild;
    struct LBinaryTreeNode * rchild;
    struct LBinaryTreeNode * parent;
};
typedef struct LBinaryTreeNode *PLBTreeNode;//结点指针类型
typedef PLBTreeNode *PLBTree;//指向结点指针的指针/树根
PLBTreeNode parent_seq(PLBTreeNode p)//求父结点
{
    if(p==NULL)
        return NULL;
    else
        return p->parent;
}
PLBTreeNode leftchild_seq(PLBTreeNode p)//求左结点
{
    if(p==NULL)
        return NULL;
    else
        return p->lchild;
}
PLBTreeNode rightchild_seq(PLBTreeNode p)//求右结点
{
    if(p==NULL)
        return NULL;
    else
        return p->rchild;
}
PLBTreeNode createRest_BTree()//递归创建从根开始的二叉树
{
    PLBTreeNode  rootnode;
    char ch;
    scanf("%c ",&ch);
    if(ch=='#')
    {
        rootnode=NULL;
        return rootnode;
    }
    else
    {
        rootnode=(PLBTreeNode)malloc(sizeof(struct LBinaryTreeNode));
        if(rootnode==NULL)
        {
            printf("创建失败!\n");
            return 0;
        }
        else
        {
            rootnode->data=ch;
            rootnode->lchild=createRest_BTree();//构造左子树
            rootnode->rchild=createRest_BTree();//构造右子树
        }
    }
    return rootnode;
}
PLBTree  create_BTree(void)//创建完整二叉树
{
    PLBTree roottree=(PLBTree)malloc(sizeof(PLBTreeNode));
    if (roottree!=NULL)
        *roottree=createRest_BTree( );//递归创建从根开始的二叉树
    return roottree;
}
void visit(PLBTreeNode p)//访问结点数据
{
    printf("%c ",p->data);
}
void preOrder(PLBTreeNode p)//先序访问
{
    if (p==NULL)
        return;
    visit(p);
    preOrder(leftchild_seq(p));
    preOrder(rightchild_seq(p));
}
void inOrder(PLBTreeNode p)//中序访问
{
    if (p==NULL)
        return;
    inOrder(leftchild_seq(p));
    visit(p);
    inOrder(rightchild_seq(p));
}
void postOrder(PLBTreeNode p)//后序访问
{
    if (p==NULL)
        return;
    postOrder(leftchild_seq(p));
    postOrder(rightchild_seq(p));
    visit(p);
}
int main()
{
    PLBTree tree=create_BTree();//结束输入#
    preOrder(*tree);
    putchar('\n');
    inOrder(*tree);
    putchar('\n');
    postOrder(*tree);
    return 0;
}

标签：结点,遍历,return,seq,rootnode,二叉树,NULL,PLBTreeNode
来源： https://blog.csdn.net/Yyttt_/article/details/111116706