每日一题 --- 590. N 叉树的后序遍历[力扣][Go]

func postorder(root *Node) []int {
    var ans []int
    var def func(*Node)
    def = func(node *Node) {
        if node == nil {
            return
        }
        for _, child := range node.Children {
            def(child)
            ans = append(ans, child.Val)
        }
    }
    if root == nil {
        return nil
    }
    def(root)
    ans = append(ans, root.Val)
    return ans
}