@@ -516,6 +516,44 @@ int sumOfLeftLeaves(struct TreeNode* root){
516516}
517517```
518518
519+ ## Scala
520+ 521+ ** 递归:**
522+ ``` scala
523+ object Solution {
524+ def sumOfLeftLeaves (root : TreeNode ): Int = {
525+ if (root == null ) return 0
526+ var midValue = 0
527+ if (root.left != null && root.left.left == null && root.left.right == null ){
528+ midValue = root.left.value
529+ }
530+ // return关键字可以省略
531+ midValue + sumOfLeftLeaves(root.left) + sumOfLeftLeaves(root.right)
532+ }
533+ }
534+ ```
535+ 536+ ** 迭代:**
537+ ``` scala
538+ object Solution {
539+ import scala .collection .mutable
540+ def sumOfLeftLeaves (root : TreeNode ): Int = {
541+ val stack = mutable.Stack [TreeNode ]()
542+ if (root == null ) return 0
543+ stack.push(root)
544+ var sum = 0
545+ while (! stack.isEmpty) {
546+ val curNode = stack.pop()
547+ if (curNode.left != null && curNode.left.left == null && curNode.left.right == null ) {
548+ sum += curNode.left.value // 如果满足条件就累加
549+ }
550+ if (curNode.right != null ) stack.push(curNode.right)
551+ if (curNode.left != null ) stack.push(curNode.left)
552+ }
553+ sum
554+ }
555+ }
556+ ```
519557
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521559<div align =" center " ><img src =https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width =500 > </img ></div >
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