题目:
题解:
func maxDepth(root *TreeNode) int {if root == nil {return 0}queue := []*TreeNode{}queue = append(queue, root)ans := 0for len(queue) > 0 {sz := len(queue)for sz > 0 {node := queue[0]queue = queue[1:]if node.Left != nil {queue = append(queue, node.Left)}if node.Right != nil {queue = append(queue, node.Right)}sz--}ans++}return ans
}