package main

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func buildTree(preorder []int, inorder []int) *TreeNode {
	if len(preorder) == 0 || len(preorder) != len(inorder) {
		return nil
	}
	root := TreeNode{preorder[0], nil, nil}
	return &root
}

func main() {
	printTree(buildTree(
		[]int{3, 9, 20, 15, 7},
		[]int{9, 3, 15, 20, 7}))
}