Merge pull request #1397 from wzqwtt/tree09

添加(0404.左叶子之和、0513.找树左下角的值)Scala版本
This commit is contained in:
程序员Carl
2022-06-26 11:11:35 +08:00
committed by GitHub
2 changed files with 81 additions and 0 deletions

View File

@ -516,6 +516,44 @@ int sumOfLeftLeaves(struct TreeNode* root){
}
```
## Scala
**递归:**
```scala
object Solution {
def sumOfLeftLeaves(root: TreeNode): Int = {
if(root == null) return 0
var midValue = 0
if(root.left != null && root.left.left == null && root.left.right == null){
midValue = root.left.value
}
// return关键字可以省略
midValue + sumOfLeftLeaves(root.left) + sumOfLeftLeaves(root.right)
}
}
```
**迭代:**
```scala
object Solution {
import scala.collection.mutable
def sumOfLeftLeaves(root: TreeNode): Int = {
val stack = mutable.Stack[TreeNode]()
if (root == null) return 0
stack.push(root)
var sum = 0
while (!stack.isEmpty) {
val curNode = stack.pop()
if (curNode.left != null && curNode.left.left == null && curNode.left.right == null) {
sum += curNode.left.value // 如果满足条件就累加
}
if (curNode.right != null) stack.push(curNode.right)
if (curNode.left != null) stack.push(curNode.left)
}
sum
}
}
```
-----------------------
<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

View File

@ -546,7 +546,50 @@ func findBottomLeftValue(_ root: TreeNode?) -> Int {
}
```
## Scala
递归版本:
```scala
object Solution {
def findBottomLeftValue(root: TreeNode): Int = {
var maxLeftValue = 0
var maxLen = Int.MinValue
// 递归方法
def traversal(node: TreeNode, leftLen: Int): Unit = {
// 如果左右都为空并且当前深度大于最大深度,记录最左节点的值
if (node.left == null && node.right == null && leftLen > maxLen) {
maxLen = leftLen
maxLeftValue = node.value
}
if (node.left != null) traversal(node.left, leftLen + 1)
if (node.right != null) traversal(node.right, leftLen + 1)
}
traversal(root, 0) // 调用方法
maxLeftValue // return关键字可以省略
}
}
```
层序遍历:
```scala
import scala.collection.mutable
def findBottomLeftValue(root: TreeNode): Int = {
val queue = mutable.Queue[TreeNode]()
queue.enqueue(root)
var res = 0 // 记录每层最左侧结果
while (!queue.isEmpty) {
val len = queue.size
for (i <- 0 until len) {
val curNode = queue.dequeue()
if (i == 0) res = curNode.value // 记录最最左侧的节点
if (curNode.left != null) queue.enqueue(curNode.left)
if (curNode.right != null) queue.enqueue(curNode.right)
}
}
res // 最终返回结果return关键字可以省略
}
```
-----------------------
<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>