diff --git a/problems/0112.路径总和.md b/problems/0112.路径总和.md index 41463ec1..6bf32ae9 100644 --- a/problems/0112.路径总和.md +++ b/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 + } +} +``` -----------------------