添加 0112.路径总和.md Scala版本

problems/0112.路径总和.md

@@ -300,7 +300,7 @@ public:
 
 ## java
 
-lc112
+### 0112.路径总和
 ```java
 class solution {
    public boolean haspathsum(treenode root, int targetsum) {
@@ -373,7 +373,7 @@ class solution {
 
 ```
 
-0113.路径总和-ii
+### 0113.路径总和-ii
 
 ```java
 class solution {
@@ -436,7 +436,7 @@ class Solution {
 
 ## python
 
-0112.路径总和
+### 0112.路径总和
 
 **递归**
 ```python
@@ -488,7 +488,7 @@ class solution:
         return false
 ```
 
-0113.路径总和-ii 
+### 0113.路径总和-ii 
 
 **递归**
 ```python
@@ -545,7 +545,7 @@ class Solution:
 
 ## go
 
-112. 路径总和
+### 112. 路径总和
 
 ```go
 //递归法
@@ -570,7 +570,7 @@ func hasPathSum(root *TreeNode, targetSum int) bool {
 }
 ```
 
-113. 路径总和 II
+### 113. 路径总和 II
 
 ```go
 /**
@@ -612,7 +612,7 @@ func traverse(node *TreeNode, result *[][]int, currPath *[]int, targetSum int) {
 
 ## javascript
 
-0112.路径总和
+### 0112.路径总和
 
 **递归**
 ```javascript
@@ -673,7 +673,7 @@ let hasPathSum = function(root, targetSum) {
 };
 ```
 
-0113.路径总和-ii 
+### 0113.路径总和-ii 
 
 **递归**
 ```javascript
@@ -768,7 +768,7 @@ let pathSum = function(root, targetSum) {
 
 ## TypeScript
 
-> 0112.路径总和
+### 0112.路径总和
 
 **递归法：**
 
@@ -850,7 +850,7 @@ function hasPathSum(root: TreeNode | null, targetSum: number): boolean {
 };
 ```
 
-> 0112.路径总和 ii
+### 0112.路径总和 ii
 
 **递归法：**
 
@@ -888,7 +888,7 @@ function pathSum(root: TreeNode | null, targetSum: number): number[][] {
 
 ## Swift
 
-0112.路径总和
+### 0112.路径总和
 
 **递归**
 
@@ -955,7 +955,7 @@ func hasPathSum(_ root: TreeNode?, _ targetSum: Int) -> Bool {
 }
 ```
 
-0113.路径总和 II
+### 0113.路径总和 II
 
 **递归**
 
@@ -1006,7 +1006,90 @@ func traversal(_ cur: TreeNode?, count: Int) {
 }
 ```
 
+## Scala
 
+### 0112.路径总和
+
+**递归:**
+```scala
+object Solution {
+  def hasPathSum(root: TreeNode, targetSum: Int): Boolean = {
+    if(root == null) return false
+    var res = false
+
+    def traversal(curNode: TreeNode, sum: Int): Unit = {
+      if (res) return // 如果直接标记为true了，就没有往下递归的必要了
+      if (curNode.left == null && curNode.right == null && sum == targetSum) {
+        res = true
+        return
+      }
+      // 往下递归
+      if (curNode.left != null) traversal(curNode.left, sum + curNode.left.value)
+      if (curNode.right != null) traversal(curNode.right, sum + curNode.right.value)
+    }
+
+    traversal(root, root.value)
+    res // return关键字可以省略
+  }
+}
+```
+
+**迭代:**
+```scala
+object Solution {
+  import scala.collection.mutable
+  def hasPathSum(root: TreeNode, targetSum: Int): Boolean = {
+    if (root == null) return false
+    val stack = mutable.Stack[(TreeNode, Int)]()
+    stack.push((root, root.value)) // 将根节点元素放入stack
+    while (!stack.isEmpty) {
+      val curNode = stack.pop() // 取出栈顶元素
+      // 如果遇到叶子节点，看当前的值是否等于targetSum，等于则返回true
+      if (curNode._1.left == null && curNode._1.right == null && curNode._2 == targetSum) {
+        return true
+      }
+      if (curNode._1.right != null) stack.push((curNode._1.right, curNode._2 + curNode._1.right.value))
+      if (curNode._1.left != null) stack.push((curNode._1.left, curNode._2 + curNode._1.left.value))
+    }
+    false //如果没有返回true，即可返回false，return关键字可以省略
+  }
+}
+```
+
+### 0113.路径总和 II
+
+**递归:**
+```scala
+object Solution {
+  import scala.collection.mutable.ListBuffer
+  def pathSum(root: TreeNode, targetSum: Int): List[List[Int]] = {
+    val res = ListBuffer[List[Int]]()
+    if (root == null) return res.toList
+    val path = ListBuffer[Int]();
+
+    def traversal(cur: TreeNode, count: Int): Unit = {
+      if (cur.left == null && cur.right == null && count == 0) {
+        res.append(path.toList)
+        return
+      }
+      if (cur.left != null) {
+        path.append(cur.left.value)
+        traversal(cur.left, count - cur.left.value)
+        path.remove(path.size - 1)
+      }
+      if (cur.right != null) {
+        path.append(cur.right.value)
+        traversal(cur.right, count - cur.right.value)
+        path.remove(path.size - 1)
+      }
+    }
+
+    path.append(root.value)
+    traversal(root, targetSum - root.value)
+    res.toList
+  }
+}
+```
 
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