LeetCode "Construct Binary Tree from Preorder and Inorder Traversal"

class Solution {
public:
TreeNode *_buildTree(int pre[], int &inx_p, int np, int in[], int i0, int i1)
{
if(inx_p == np || i0 == i1) return NULL;

TreeNode *pRoot = new TreeNode(pre[inx_p]);

int inx = std::find(in + i0, in + i1, pre[inx_p++]) - in;

TreeNode *pLeft = _buildTree(pre, inx_p, np, in, i0, inx);
TreeNode *pRight = _buildTree(pre, inx_p, np, in, inx + 1, i1);
pRoot->left = pLeft; pRoot->right = pRight;
return pRoot;

}
TreeNode *buildTree(vector<int> &preorder, vector<int> &inorder) {
int *pre = new int[preorder.size()];
std::copy(preorder.begin(), preorder.end(), pre);
int *in = new int[inorder.size()];
std::copy(inorder.begin(), inorder.end(), in);
int inx = 0;
return _buildTree(pre, inx, preorder.size(), in, 0, inorder.size());
}
};