二叉树的递归遍历

#include<stdio.h>
#include<stdlib.h>

typedef char ElemType;
typedef char DataType;


//二叉链表存储结构
typedef struct BiTNode
{
	DataType data;
	struct BiTNode *lchild;
	struct BiTNode *rchild;
}BiTNode,*BiTree; //BiTNode为结点类型，BiTree为指向二叉链表结点的指针类型

D表示访问根结点
L表示访问根节点的左子树
R表示访问根节点的右子树

//1.DLR 先序遍历
void preorder(BiTree T)
{
	if(T)
	{
		printf("%c",T->data);
		preorder(T->lchild);
		preorder(T->rchild);
	}
}

//2.LDR中序遍历
void inorder(BiTree T)
{
	if(T)
	{
		inorder(T->lchild);
		printf("%c",T->data);
		inorder(T->rchild);
	}
}

//3.LRD后序遍历
void postorder(BiTree T)
{
	if(T)
	{
		postorder(T->lchild);
		postorder(T->rchild);
		printf("%c",T->data);
	}
}

void main()
{
	BiTree T=(BiTree)malloc(sizeof(BiTNode));
	//初始化一个二叉树，其根节点是A,没有左右孩子
	T->data='A';
	T->lchild=NULL;
	T->rchild=NULL;
	preorder(T);
	printf("\n");

	T->lchild=(BiTree)malloc(sizeof(BiTNode));
	T->lchild->data='B';
	T->lchild->lchild=NULL;
	T->lchild->rchild=NULL;

	T->rchild=(BiTree)malloc(sizeof(BiTNode));
	T->rchild->data='C';
	T->rchild->lchild=NULL;
	T->rchild->rchild=NULL;
	preorder(T);
	printf("\n");

	T->lchild->lchild=(BiTree)malloc(sizeof(BiTNode));
	T->lchild->lchild->data='D';
	T->lchild->lchild->lchild=NULL;
	T->lchild->lchild->rchild=(BiTree)malloc(sizeof(BiTNode));
	T->lchild->lchild->rchild->data='G';
	T->lchild->lchild->rchild->lchild=NULL;
	T->lchild->lchild->rchild->rchild=NULL;

	T->rchild->lchild=(BiTree)malloc(sizeof(BiTNode));
	T->rchild->lchild->data='E';
	T->rchild->lchild->lchild=NULL;
	T->rchild->lchild->rchild=NULL;
	T->rchild->rchild=(BiTree)malloc(sizeof(BiTNode));
	T->rchild->rchild->data='F';
	T->rchild->rchild->lchild=NULL;
	T->rchild->rchild->rchild=NULL;
	printf("先序遍历:");
	preorder(T);
	printf("\n");
	printf("中序遍历:");	
	inorder(T);
	printf("\n");
	printf("后序遍历:\n");
	postorder(T);
}

运行结果