class Solution {
public:
    TreeNode* mergeTrees(TreeNode* root1, TreeNode* root2) {
        if(!root1) return root2;
        if(!root2) return root1;

        TreeNode* mergeTree = new TreeNode(root1->val+root2->val);
        mergeTree->left = mergeTrees(root1->left,root2->left);
        mergeTree->right = mergeTrees(root1->right,root2->right);

        return mergeTree;
    }
};