scala leetcode 559

scala-leetcode/README.md

@@ -1022,4 +1022,35 @@
     }
     ret
   }
+```
+* N叉树的最大深度
+```scala
+ //DFS
+  def maxDepth(root: Node): Int = {
+    if (root == null) return 0
+    var depth = 0
+    for (i <- root.children.indices) {
+      depth = Math.max(depth, maxDepth(root.children(i)))
+    }
+    depth + 1
+  }
+
+  //层序遍历
+  def maxDepth2(root: Node): Int = {
+    if (root == null) return 0
+    if (root.children.isEmpty) return 1
+    var depth = 0
+    var queue = root :: List()
+    while (queue.nonEmpty) {
+      depth += 1
+      queue.indices foreach { _ =>
+        val node = queue.take(1).headOption
+        queue = queue.drop(1)
+        if (node.fold(false)(_.children.nonEmpty)) {
+          queue = queue ::: node.fold(List[Node]())(_.children)
+        }
+      }
+    }
+    depth
+  }
 ```
\ No newline at end of file

scala-leetcode/src/main/scala/io/github/dreamylost/Leetcode_559.scala

+package io.github.dreamylost
+
+/**
+ * 559. N叉树的最大深度
+ *
+ * @author 梦境迷离
+ * @since 2020-04-23
+ * @version v1.0
+ */
+object Leetcode_559 extends App {
+
+  val node5 = new Node(5)
+  val node6 = new Node(6)
+  val node3 = new Node(3)
+  val node2 = new Node(2)
+  val node4 = new Node(4)
+  val node1 = new Node(1)
+
+  node3.children = List(node5, node6)
+  node1.children = List(node3, node2, node4)
+
+  println(maxDepth(node1))
+  println(maxDepth2(node1))
+
+  //N叉树
+  class Node(var _value: Int) {
+    var value: Int = _value
+    var children: List[Node] = List()
+  }
+
+  //DFS
+  def maxDepth(root: Node): Int = {
+    if (root == null) return 0
+    var depth = 0
+    for (i <- root.children.indices) {
+      depth = Math.max(depth, maxDepth(root.children(i)))
+    }
+    depth + 1
+  }
+
+  //层序遍历
+  def maxDepth2(root: Node): Int = {
+    if (root == null) return 0
+    if (root.children.isEmpty) return 1
+    var depth = 0
+    var queue = root :: List()
+    while (queue.nonEmpty) {
+      depth += 1
+      queue.indices foreach { _ =>
+        val node = queue.take(1).headOption
+        queue = queue.drop(1)
+        if (node.fold(false)(_.children.nonEmpty)) {
+          queue = queue ::: node.fold(List[Node]())(_.children)
+        }
+      }
+    }
+    depth
+  }
+}