add scala #662

build_before_commit.sh

@@ -7,7 +7,6 @@ root_path=`pwd`
 # auto compile java and scala
 `gradle -s build > java_scala_compile.log`
 `gradle -s spotlessApply >> java_scala_compile.log`
-`gradle -s build >> java_scala_compile.log`
 
 for sub_module in $(ls $root_path)
 do

scala-leetcode/README.md

@@ -68,6 +68,7 @@ Leetcode Scala 实现
 * [求根到叶子节点数字之和](./src/main/scala/io/github/dreamylost/Leetcode_129.scala)
 * [二叉树的前序遍历 迭代](./src/main/scala/io/github/dreamylost/Leetcode_129.scala)
 * [二叉搜索树迭代器](./src/main/scala/io/github/dreamylost/Leetcode_173.scala)
+* [二叉树最大宽度](./src/main/scala/io/github/dreamylost/Leetcode_662.scala)
 
 ## 链表
 

scala-leetcode/src/main/scala/io/github/dreamylost/Leetcode_662.scala

+/* Licensed under Apache-2.0 @梦境迷离 */
+package io.github.dreamylost
+
+/**
+  * 662. 二叉树最大宽度
+  *
+  * 给定一个二叉树，编写一个函数来获取这个树的最大宽度。树的宽度是所有层中的最大宽度。这个二叉树与满二叉树（full binary tree）结构相同，但一些节点为空。
+  *
+  * 每一层的宽度被定义为两个端点（该层最左和最右的非空节点，两端点间的null节点也计入长度）之间的长度。
+  *
+  * @see https://github.com/jxnu-liguobin/cs-summary-reflection
+  * @author 梦境迷离
+  * @version 1.0,2020/7/22
+  */
+object Leetcode_662 extends App {
+
+  val ret = widthOfBinaryTree(TreeNodeData.treeData3())
+  println(ret)
+
+  /**
+    * 层序遍历，记录每个节点的索引
+    * 600 ms,100.00%
+    * 51.6 MB,100.00%
+    *
+    * @param root
+    * @return
+    */
+  def widthOfBinaryTree(root: TreeNode): Int = {
+    if (root == null) return 0
+    if (root.left == null && root.right == null) return 1
+    var ret = 1
+    var nodeQueue = List[TreeNode]()
+    nodeQueue = nodeQueue ::: List(root)
+    var indexedQueue = Seq.empty[Int]
+    indexedQueue = indexedQueue ++ Seq(1)
+    var size = 1
+    while (nodeQueue.nonEmpty) {
+      size -= 1
+      val index = indexedQueue.head
+      indexedQueue = indexedQueue.tail
+      val node = nodeQueue.head
+      nodeQueue = nodeQueue.tail
+      //根据满二叉树子树下标与父节点的关系，记录左右子树的下标位置
+      if (node.left != null) {
+        nodeQueue = nodeQueue ::: List(node.left)
+        indexedQueue = indexedQueue ++ Seq(2 * index)
+      }
+      if (node.right != null) {
+        nodeQueue = nodeQueue ::: List(node.right)
+        indexedQueue = indexedQueue ++ Seq(2 * index + 1)
+      }
+      //在遍历完当前层时，判断下标是否存在大于2个以上的元素，就使用两个边界计算宽度
+      if (size == 0) {
+        if (indexedQueue.size >= 2) {
+          ret = math.max(ret, indexedQueue.last - indexedQueue.head + 1)
+        }
+        size = nodeQueue.size
+      }
+    }
+    ret
+  }
+}