二叉树层次遍历

#include <iostream>
#include <queue>
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;
}

void cengci_show(Node* root)
{
	queue<Node*> q;
	q.push(root);
	while (!q.empty())
	{
		Node* tmp = q.front();
		q.pop();
		cout << tmp->data << " ";
		if (tmp->left != NULL)
		{
			q.push(tmp->left);
		}
		if (tmp->right != NULL)
		{
			q.push(tmp->right);
		}
	}
}

int main()
{
	Node* root = insert();
	cengci_show(root);
	return 0;
}