golang 解法, 执行用时: 4 ms, 内存消耗: 3.5 MB, 提交时间: 2021-06-10 21:12:43

/**
 * Definition for a Node.
 * type Node struct {
 *     Val int
 *     Children []*Node
 * }
 */

func maxDepth(root *Node) int {
    if root == nil {
        return 0
    } else if len(root.Children) == 0 {
        return 1
    } else {
        var heights []int
        for _, node := range root.Children {
            heights = append(heights, maxDepth(node)+1)
        }
        return max(heights)
    }
}

func max(arr []int) int {
    m := 0
    for _, a := range arr {
        if a > m {
            m = a
        }
    }
    return m
}