@@ -631,7 +631,60 @@ function mergeTrees(root1: TreeNode | null, root2: TreeNode | null): TreeNode |
631631};
632632```
633633
634+ ## Scala
635+ 636+ 递归:
637+ ``` scala
638+ object Solution {
639+ def mergeTrees (root1 : TreeNode , root2 : TreeNode ): TreeNode = {
640+ if (root1 == null ) return root2 // 如果root1为空,返回root2
641+ if (root2 == null ) return root1 // 如果root2为空,返回root1
642+ // 新建一个节点,值为两个节点的和
643+ var node = new TreeNode (root1.value + root2.value)
644+ // 往下递归
645+ node.left = mergeTrees(root1.left, root2.left)
646+ node.right = mergeTrees(root1.right, root2.right)
647+ node // 返回node,return关键字可以省略
648+ }
649+ }
650+ ```
634651
652+ 迭代:
653+ ``` scala
654+ object Solution {
655+ import scala .collection .mutable
656+ def mergeTrees (root1 : TreeNode , root2 : TreeNode ): TreeNode = {
657+ if (root1 == null ) return root2
658+ if (root2 == null ) return root1
659+ var stack = mutable.Stack [TreeNode ]()
660+ // 先放node2再放node1
661+ stack.push(root2)
662+ stack.push(root1)
663+ while (! stack.isEmpty) {
664+ var node1 = stack.pop()
665+ var node2 = stack.pop()
666+ node1.value += node2.value
667+ if (node1.right != null && node2.right != null ) {
668+ stack.push(node2.right)
669+ stack.push(node1.right)
670+ } else {
671+ if (node1.right == null ){
672+ node1.right = node2.right
673+ }
674+ }
675+ if (node1.left != null && node2.left != null ) {
676+ stack.push(node2.left)
677+ stack.push(node1.left)
678+ } else {
679+ if (node1.left == null ){
680+ node1.left = node2.left
681+ }
682+ }
683+ }
684+ root1
685+ }
686+ }
687+ ```
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