scala leetcode 1022

scala-leetcode/README.md

@@ -43,6 +43,7 @@ Leetcode Scala 实现
 * [单值二叉树](./src/main/scala/io/github/dreamylost/Leetcode_965.scala)
 * [对称的二叉树](./src/main/scala/io/github/dreamylost/Leetcode_JZ_28.scala)
 * [平衡二叉树](./src/main/scala/io/github/dreamylost/Leetcode_JZ_55_2.scala)
+* [从根到叶的二进制数之和](./src/main/scala/io/github/dreamylost/Leetcode_1022.scala)
 
 ## 链表
 

scala-leetcode/src/main/scala/io/github/dreamylost/Leetcode_1022.scala

+package io.github.dreamylost
+
+/**
+ * 1022. 从根到叶的二进制数之和
+ *
+ * 给出一棵二叉树，其上每个结点的值都是 0 或 1 。每一条从根到叶的路径都代表一个从最高有效位开始的二进制数。例如，如果路径为 0 -> 1 -> 1 -> 0 -> 1，那么它表示二进制数 01101，也就是 13 。
+ *
+ * 对树上的每一片叶子，我们都要找出从根到该叶子的路径所表示的数字。以 10^9 + 7 为模，返回这些数字之和。
+ * @author 梦境迷离 dreamylost
+ * @since 2020-06-23
+ * @version v1.0
+ */
+object Leetcode_1022 extends App {
+
+  val ret = sumRootToLeaf(TreeNodeData.treeData3_6())
+  val ret2 = sumRootToLeaf2(TreeNodeData.treeData3_6())
+  println(ret)
+  println(ret2)
+
+  /**
+   * Scala不能更新形参，dfs时只能记录到当前节点上
+   *
+   * 540 ms,100.00%
+   * 51.5 MB,100.00%
+   *
+   * @param root
+   * @return
+   */
+  def sumRootToLeaf(root: TreeNode): Int = {
+    val mod = 1000000007
+
+    def dfs(r: TreeNode): Int = {
+      if (r == null) return 0
+      val temp = r.value % mod
+      if (r.left == null && r.right == null) {
+        return temp
+      }
+      if (r.left != null) r.left.value += temp << 1
+      if (r.right != null) r.right.value += temp << 1
+      (dfs(r.left) + dfs(r.right)) % mod
+    }
+
+    dfs(root)
+  }
+
+  /**
+   * 硬解，计算路径的所有和
+   * 604 ms,25.00%
+   * 51.7 MB,100.00%
+   *
+   * @param root
+   * @return
+   */
+  def sumRootToLeaf2(root: TreeNode): Int = {
+    val mod = 1000000007
+    var result = Seq[String]()
+
+    //s必须传值
+    def helper(r: TreeNode, path: String): Unit = {
+      if (r == null) return
+      if (r.left == null && r.right == null) {
+        result = result ++ Seq(path + r.value + "")
+        return
+      }
+      if (r.left != null) helper(r.left, path + r.value + "")
+      if (r.right != null) helper(r.right, path + r.value + "")
+    }
+
+    helper(root, new String)
+    result.map(r => java.lang.Long.parseLong(r, 2) % mod).sum.asInstanceOf[Int]
+  }
+}

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

@@ -68,6 +68,16 @@ object TreeNodeData {
     root
   }
 
+  //10 11
+  def treeData3_6(): TreeNode = {
+    val root = new TreeNode(1)
+    val r1 = new TreeNode(1)
+    val l1 = new TreeNode(0)
+    root.right = r1
+    root.left = l1
+    root
+  }
+
   def treeData5_1(): TreeNode = {
     val n1 = new TreeNode(1)
     val n2 = new TreeNode(2)