力扣-二叉树-617 合并二叉树

思路

先序遍历合并

代码

class Solution {
public:
    TreeNode* mergeTrees(TreeNode* root1, TreeNode* root2) {
        if(root1 != nullptr && root2 != nullptr){
            root1->val += root2->val;
            root1->left = mergeTrees(root1->left, root2->left);
            root1->right = mergeTrees(root1->right, root2->right);
        }else if(root1 == nullptr && root2 != nullptr){
            root1 = root2;
        }else if(root1 != nullptr && root2 == nullptr){
            return root1;
        }

        return root1;
    }
};