二叉树的创建与前中后序遍历

#include <iostream>
using namespace std;

struct Node {
	int data;
	Node* right;
	Node* left;
};
//二叉树的创建
Node* insert() {
	cout << "输入要插入的数字，以0结束：" << endl;
	int data;
	cin >> data;
	Node* root;
	root = (Node*)malloc(sizeof(Node));
	root->right = NULL;
	root->left = NULL;
	root->data = NULL;
	if (data == 0)
		return root;
	else
		root->data = data;
	cin >> data;
	while (data != 0) {
		Node* p = root;
		//p->data = data;
		Node* q = p;
		while (p != NULL) {
			if (data > p->data) {
				q = p;
				p = q->right;
			}
			else if(data < p->data)
			{
				q = p;
				p = q->left;
			}
			else if (data == p->data)
			{
				break;
			}
		}
		Node* tmp;
		tmp = (Node*)malloc(sizeof(Node));
		tmp->data = data;
		tmp->left = NULL;
		tmp->right = NULL;
		if (data > q->data) {
			q->right = tmp;
		}
		else if (data < q->data)
		{
			q->left = tmp;
		}
		//else if (data == q->data)
		//{
		//	cin >> data;
		//	continue;
		//}
		cin >> data;
	}
	return root;
}
//二叉树的前序遍历
void PreOrderTree(Node* root) {
	Node* p = root;
	if (p != NULL)
	{
		cout << p->data << endl;
		PreOrderTree(p->left);
		PreOrderTree(p->right);
	}
}

//二叉树的中序遍历
void InOrderTree(Node* root) {
	Node* p = root;
	if (p != NULL)
	{
		InOrderTree(p->left);
		cout << p->data << endl;
		InOrderTree(p->right);
	}
}
//二叉树的后序遍历
void PostOrderTree(Node* root) {
	Node* p = root;
	if (p != NULL)
	{
		PostOrderTree(p->left);
		PostOrderTree(p->right);
		cout << p->data << endl;
	}
}

int main()
{
	cout << "=======创建一个二叉树========" << endl;
	Node* root = insert();
	cout << "=======二叉树的前序遍历========" << endl;
	PreOrderTree(root);
	cout << "=======二叉树的中序遍历========" << endl;
	InOrderTree(root);
	cout << "=======二叉树的后序遍历========" << endl;
	PostOrderTree(root);
	return 0;
}

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