# golang_max_tree_depth

Given the `root` of a binary tree, return its maximum depth.

A binary tree’s maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

## Examples

Example 1:

``````Input: root = [3,9,20,null,null,15,7]
Output: 3

``````

Example 2:

``````Input: root = [1,null,2]
Output: 2

``````

Constraints:

• The number of nodes in the tree is in the range `[\$0, 10^4\$]`.
• `100 <= Node.val <= 100`

## 程式碼

```package sol

/**
* Definition for a binary tree node.
* type TreeNode struct {
*     Val int
*     Left *TreeNode
*     Right *TreeNode
* }
*/
func maxDepth(root *TreeNode) int {
return FindMaxDepth(root)
}

func FindMaxDepth(root *TreeNode) int {
if root == nil {
return 0
}
return Max(FindMaxDepth(root.Left), FindMaxDepth(root.Right)) + 1
}

func Max(i, j int) int {
if i > j {
return i
}
return j
}```

## 困難點

1. 要思考出二元樹最大深度的關係式
2. 知道邊界條件

## Solve Point

• Understand What problem need to solve
• Analysis Complexity

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