Construct Binary Tree from Preorder and Inorder Traversal

recursion programming

public class Solution {
    public TreeNode buildTree(int[] preorder, int[] inorder) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        if(preorder == null)
            return null;
        return buildTree(preorder, inorder, 0, preorder.length, 0, inorder.length);
    }
    
    private TreeNode buildTree(int[] preorder, int[] inorder, int preorderStart, int preorderEnd, int inorderStart, int inorderEnd)
    {
        if(preorderStart >= preorderEnd)
            return null;
        TreeNode tmp = new TreeNode(preorder[preorderStart]);
        if(preorderEnd - preorderStart == 1)
            return tmp;
        int newinorderStart = inorderStart;
        
        while(inorder[newinorderStart] != preorder[preorderStart])
        {
            newinorderStart++;
        }
        
        int newpreorderStart = preorderStart + 1;
        int newpreorderEnd = newpreorderStart + (newinorderStart - inorderStart);
        tmp.left = buildTree(preorder, inorder, newpreorderStart, newpreorderEnd, inorderStart, newinorderStart);
        tmp.right = buildTree(preorder, inorder, newpreorderEnd, preorderEnd, newinorderStart+1, inorderEnd);
        return tmp;
    }
}