#创建树及先序&中序创建树_创建treenode

struct TreeNode {
	char data;
	TreeNode* lchild;
	TreeNode* rchild;
};
//#号法创建树 先序创建
TreeNode* createTree() {
	TreeNode* node = NULL;
	TreeNode* pL = NULL;
	TreeNode* pR = NULL;
	char h;
	scanf("%c", &h);
	cout << "h:  " << h << endl;
	if (h == '#') {
		return NULL;
	}
	else {
		node = new TreeNode;
		memset(node, 0, sizeof(TreeNode));
		node->data = h;
		pL = createTree();
		if (pL != NULL) {
			node->lchild = pL;
			cout << "pL data: " << pL->data << endl;;
		}
		else {
			node->lchild = NULL;
			cout << "pL data: NULL" <<  endl;;
		}
		pR = createTree();
		if (pR != NULL) {
			node->rchild = pR;
			cout << "pR data: " << pR->data << endl;;
		}
		else {
			node->rchild = NULL;
			cout << "pR data: NULL" <<  endl;;
		}
	}
	return node;
}
//先序创建树 用后序释放
void deleteTree(TreeNode* node) {
	if (node == NULL) {
		return ;
	}
	if (node->lchild != NULL) {
		deleteTree(node->lchild);
		node->lchild = NULL;
	}
	if (node->rchild != NULL) {
		deleteTree(node->rchild);
		node->rchild = NULL;
	}
	if (node != NULL) {
		deleteTree(node);
		node == NULL;
	}
}
void preMethood(TreeNode* root) {
	if (root == NULL) {
		return;
	}
	cout << " preMethood: " << root->data << " ";
	preMethood(root->lchild);
	preMethood(root->rchild);
}
/*
先序遍历和中序遍历生成树
1.通过先序遍历找到根节点A,再通过中序遍历的位置找出左子树，右子树
2.在A的左子树中，找左子树的根节点（在先序遍历中找），转1
3.在A的右子树中，找右子树的根节点（在先序遍历中找），转1
先序遍历：ADEBCF
中序遍历：DEACFB
*/
TreeNode* createTreeByPreAndMed(char* pre, char* med, int length) {
	TreeNode* node = new TreeNode;
	node->data = pre[0];
	node->lchild = NULL;
	node->rchild = NULL;
	cout << "crtdata: " << node->data << endl;
	if (length == 0) {
		return NULL;
	}
	if (length == 1) {
		return node;
	}
	char data[2] = { pre[0],'\0' };
	char* finddata = strstr(med, data);
	int len = finddata - med;
	cout << "findleft:  " << pre + 1 << endl;
	node->lchild = createTreeByPreAndMed(pre + 1, med, len);
	cout << " findright: " << pre + len + 1 << endl;
	node->rchild = createTreeByPreAndMed(pre + len + 1, med + len + 1, length - len - 1);
	cout << "crtdata: " << node->data << " lchild: " << node->lchild->data << " rchild: " << node->rchild->data << endl;
	return node;
}
int main() {
	char* str1 = "124895367";
	char* str2 = "849251637";
	createTreeByPreAndMed(str1, str2, strlen(str1));
	system("pause");
	return 0;
}
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