添加 104.二叉树的最大深度 Scala版本

problems/0102.二叉树的层序遍历.md

@@ -2160,6 +2160,30 @@ func maxDepth(_ root: TreeNode?) -> Int {
 }
 ```
 
+Scala:
+```scala
+// 104.二叉树的最大深度
+object Solution {
+  import scala.collection.mutable
+  def maxDepth(root: TreeNode): Int = {
+    if (root == null) return 0
+    val queue = mutable.Queue[TreeNode]()
+    queue.enqueue(root)
+    var depth = 0
+    while (!queue.isEmpty) {
+      val len = queue.length
+      depth += 1
+      for (i <- 0 until len) {
+        val curNode = queue.dequeue()
+        if (curNode.left != null) queue.enqueue(curNode.left)
+        if (curNode.right != null) queue.enqueue(curNode.right)
+      }
+    }
+    depth
+  }
+}
+```
+
 # 111.二叉树的最小深度
 
 [力扣题目链接](https://leetcode-cn.com/problems/minimum-depth-of-binary-tree/)