二叉树的构建和遍历

#include <iostream>
using namespace std;
const int N = 9;
int order[1 << N], k = 0;
struct TreeNode {
	int val;
	TreeNode *leftChild;
	TreeNode *rightChild;
	TreeNode() : TreeNode(0) {}
	TreeNode(int x) : val(x), leftChild(nullptr), rightChild(nullptr) {}
};
int number;
void createBinaryTree(TreeNode *&root)
{

	cin >> number;
	if (number == -1)
		return;
	root = new TreeNode(number);
	createBinaryTree(root->leftChild);
	createBinaryTree(root->rightChild);
}

void preOrderTraverse(TreeNode *root, int order[], int *k) {
	if (root == nullptr)
		return;
	order[(*k)++] = root->val;
	preOrderTraverse(root->leftChild, order, k);
	preOrderTraverse(root->rightChild, order, k);
}

void inOrderTraverse(TreeNode *root, int order[], int *k)
{
	if (root == nullptr)return;
	inOrderTraverse(root->leftChild, order, k);
	order[(*k)++] = root->val;
	inOrderTraverse(root->rightChild, order, k);
}

void postOrderTraverse(TreeNode *root, int order[], int *k)
{
	if (root == nullptr)return;
	postOrderTraverse(root->leftChild, order, k);

	postOrderTraverse(root->rightChild, order, k);
	order[(*k)++] = root->val;
}
void print()
{
	for (int i = 0; i < k; i++)
	{
		if (i == 0)
			cout << order[i];
		else
			cout << " " << order[i];
	}
	cout << endl;
}
int main()
{
	TreeNode *root = nullptr;
	createBinaryTree(root);



	preOrderTraverse(root, order, &k);

	print();
	k = 0;
	inOrderTraverse(root, order, &k);

	print();
	k = 0;
	postOrderTraverse(root, order, &k);

	print();
	return 0;
}