From f83d5edb6ebf5cd6de1eabba51a246a921f94e1b Mon Sep 17 00:00:00 2001
From: ZongqinWang <1722249371@qq.com>
Date: Mon, 23 May 2022 19:14:45 +0800
Subject: [PATCH 1/2] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200222.=E5=AE=8C?=
=?UTF-8?q?=E5=85=A8=E4=BA=8C=E5=8F=89=E6=A0=91=E7=9A=84=E8=8A=82=E7=82=B9?=
=?UTF-8?q?=E4=B8=AA=E6=95=B0.md=20Scala=E7=89=88=E6=9C=AC?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
---
problems/0222.完全二叉树的节点个数.md | 63 +++++++++++++++++++++++++++
1 file changed, 63 insertions(+)
diff --git a/problems/0222.完全二叉树的节点个数.md b/problems/0222.完全二叉树的节点个数.md
index ba7acc5a..746d45cc 100644
--- a/problems/0222.完全二叉树的节点个数.md
+++ b/problems/0222.完全二叉树的节点个数.md
@@ -646,5 +646,68 @@ func countNodes(_ root: TreeNode?) -> Int {
}
```
+## Scala
+
+递归:
+```scala
+object Solution {
+ def countNodes(root: TreeNode): Int = {
+ if(root == null) return 0
+ 1 + countNodes(root.left) + countNodes(root.right)
+ }
+}
+```
+
+层序遍历:
+```scala
+object Solution {
+ import scala.collection.mutable
+ def countNodes(root: TreeNode): Int = {
+ if (root == null) return 0
+ val queue = mutable.Queue[TreeNode]()
+ var node = 0
+ queue.enqueue(root)
+ while (!queue.isEmpty) {
+ val len = queue.size
+ for (i <- 0 until len) {
+ node += 1
+ val curNode = queue.dequeue()
+ if (curNode.left != null) queue.enqueue(curNode.left)
+ if (curNode.right != null) queue.enqueue(curNode.right)
+ }
+ }
+ node
+ }
+}
+```
+
+利用完全二叉树性质:
+```scala
+object Solution {
+ def countNodes(root: TreeNode): Int = {
+ if (root == null) return 0
+ var leftNode = root.left
+ var rightNode = root.right
+ // 向左向右往下探
+ var leftDepth = 0
+ while (leftNode != null) {
+ leftDepth += 1
+ leftNode = leftNode.left
+ }
+ var rightDepth = 0
+ while (rightNode != null) {
+ rightDepth += 1
+ rightNode = rightNode.right
+ }
+ // 如果相等就是一个满二叉树
+ if (leftDepth == rightDepth) {
+ return (2 << leftDepth) - 1
+ }
+ // 如果不相等就不是一个完全二叉树，继续向下递归
+ countNodes(root.left) + countNodes(root.right) + 1
+ }
+}
+```
+
-----------------------
From 45a3c91a7a954947d6b7373bee876d2f498e26bd Mon Sep 17 00:00:00 2001
From: ZongqinWang <1722249371@qq.com>
Date: Mon, 23 May 2022 19:49:18 +0800
Subject: [PATCH 2/2] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200257.=E4=BA=8C?=
=?UTF-8?q?=E5=8F=89=E6=A0=91=E7=9A=84=E6=89=80=E6=9C=89=E8=B7=AF=E5=BE=84?=
=?UTF-8?q?.md=20Scala=E7=89=88=E6=9C=AC?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
---
problems/0257.二叉树的所有路径.md | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/problems/0257.二叉树的所有路径.md b/problems/0257.二叉树的所有路径.md
index 1362897c..70a3c66f 100644
--- a/problems/0257.二叉树的所有路径.md
+++ b/problems/0257.二叉树的所有路径.md
@@ -702,5 +702,35 @@ func binaryTreePaths(_ root: TreeNode?) -> [String] {
}
```
+Scala:
+
+递归:
+```scala
+object Solution {
+ import scala.collection.mutable.ListBuffer
+ def binaryTreePaths(root: TreeNode): List[String] = {
+ val res = ListBuffer[String]()
+ def traversal(curNode: TreeNode, path: ListBuffer[Int]): Unit = {
+ path.append(curNode.value)
+ if (curNode.left == null && curNode.right == null) {
+ res.append(path.mkString("->")) // mkString函数: 将数组的所有值按照指定字符串拼接
+ return // 处理完可以直接return
+ }
+
+ if (curNode.left != null) {
+ traversal(curNode.left, path)
+ path.remove(path.size - 1)
+ }
+ if (curNode.right != null) {
+ traversal(curNode.right, path)
+ path.remove(path.size - 1)
+ }
+ }
+ traversal(root, ListBuffer[Int]())
+ res.toList
+ }
+}
+```
+
-----------------------
