重建二叉树

#include <iostream>
#include <vector>
#include <queue>
using namespace std;

struct TreeNode {
	int val;
	TreeNode* left;
	TreeNode* right;
};

TreeNode* ConstructCore(vector<int>& preorder, int preorderLeft, int preorderRight, vector<int>& inorder, int inorderLeft, int inorderRight) {
	int headVal = preorder[preorderLeft];
	TreeNode* root = new TreeNode;
	root->val = headVal;
	root->left = nullptr;
	root->right = nullptr;
	if (preorderLeft == preorderRight)
		return root;

	vector<int>::iterator iter = inorder.begin() + inorderLeft;
	while (iter != inorder.end() && *iter != headVal) {
		iter++;
	}
	int len = iter - inorder.begin() - inorderLeft;
	if(len>0)
		root->left = ConstructCore(preorder, preorderLeft+1, preorderLeft+len, inorder, inorderLeft, inorderLeft+len-1);
	if(len< inorderRight-inorderLeft)
		root->right = ConstructCore(preorder, preorderLeft+len+1, preorderRight, inorder, inorderLeft+len+1, inorderRight);
	return root;
}

void dpsPrint(TreeNode* root) {
	queue<TreeNode*> que;
	que.push(root);
	while (!que.empty()) {
		TreeNode* temp = que.front();
		que.pop();
		if (temp->left)
			que.push(temp->left);
		if (temp->right)
			que.push(temp->right);
		cout << temp->val << " ";
	}
}

int main() {
	vector<int> preorder = { 1,2,4,7,3,5,6,8 };
	vector<int> inorder{ 4,7,2,1,5,3,8,6 };
	TreeNode* root=ConstructCore(preorder, 0, preorder.size()-1, inorder, 0, inorder.size()-1);
	dpsPrint(root);

	return 0;
}