添加 0111.二叉树的最小深度.md Scala版本

problems/0111.二叉树的最小深度.md

@@ -488,5 +488,44 @@ func minDepth(_ root: TreeNode?) -> Int {
 }
 ```
 
+## Scala
+
+递归法:
+```scala
+object Solution {
+  def minDepth(root: TreeNode): Int = {
+    if (root == null) return 0
+    if (root.left == null && root.right != null) return 1 + minDepth(root.right)
+    if (root.left != null && root.right == null) return 1 + minDepth(root.left)
+    // 如果两侧都不为空，则取最小值，return关键字可以省略
+    1 + math.min(minDepth(root.left), minDepth(root.right))
+  }
+}
+```
+
+迭代法:
+```scala
+object Solution {
+  import scala.collection.mutable
+  def minDepth(root: TreeNode): Int = {
+    if (root == null) return 0
+    var depth = 0
+    val queue = mutable.Queue[TreeNode]()
+    queue.enqueue(root)
+    while (!queue.isEmpty) {
+      depth += 1
+      val len = queue.size
+      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)
+        if (curNode.left == null && curNode.right == null) return depth
+      }
+    }
+    depth
+  }
+}
+```
+
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