数据结构与算法之 二叉树 (一)递归算法

#include<iostream>
using namespace std;

struct tree_node
{
	int data;
	tree_node *lchild;
	tree_node *rchild;
};

void create_btree(tree_node** b_tree)
{
	int c = 0;
	cin>>c;
	if(c != 0)
	{
		*b_tree = new tree_node;
		(*b_tree)->data = c;
		create_btree(&(*b_tree)->lchild);
		create_btree(&(*b_tree)->rchild);
	}
	else
	{
		*b_tree = NULL;
	}
}

void preorder(tree_node *head)
{
	if(head != NULL)
	{
		cout<<head->data<<endl;
		preorder(head->lchild);
		preorder(head->rchild);
	}
}

void inorder(tree_node *head)
{
	if(head != NULL)
	{
		inorder(head->lchild);
		cout<<head->data<<endl;
		inorder(head->rchild);
	}
}

void postorder(tree_node *head)
{
	if(head != NULL)
	{
		postorder(head->lchild);
		cout<<head->data<<endl;
		postorder(head->rchild);
	}
}


int main()
{
	tree_node *head = NULL;
    create_btree(&head);
	cout<<"前序遍历"<<endl;
	preorder(head);
	cout<<"中序遍历"<<endl;
	inorder(head);
	cout<<"后序遍历"<<endl;
	postorder(head);
	return 0;
}