package binarytreepreordertraversal

import . "gitee.com/dllearn/geektime-algorithm-learn/structures"

// 144. 二叉树的前序遍历
// https://leetcode-cn.com/problems/binary-tree-preorder-traversal/

func preorderTraversal(root *TreeNode) []int {
	res := []int{}
	dfs(root, &res)
	return res
}

func dfs(node *TreeNode, res *[]int) {
	if node != nil {
		*res = append(*res, node.Val)
		dfs(node.Left, res)
		dfs(node.Right, res)

	}
	return
}