二叉树

先序遍历：根->左->右

void order(Node*node){
	
	if(node!=NULL){
		
		cout<<node->date<<endl;
		
		preorder(node->left);
		preorder(node->right);
		
	}
} 

中序遍历：左->根->右

void order(Node*node){
	
	if(node!=NULL){
		preorder(node->left);
		
		cout<<node->date<<endl;
		
		preorder(node->right);
		
	}
} 

后序遍历：左->右->根

void order(Node*node){
	
	if(node!=NULL){
		preorder(node->left);
		preorder(node->right);
		
		cout<<node->date<<endl;
	}
}