Merge Two Binary Trees.cpp

class Solution {
public:

    TreeNode* mergeTrees(TreeNode* root1, TreeNode* root2) {
        if (root1 == NULL && root2 == NULL) return NULL;
        if (root1 == NULL) return root2;
        if (root2 == NULL) return root1;
        
        TreeNode *node = new TreeNode(root1->val + root2->val);
        
        node->left = mergeTrees(root1->left, root2->left);
        node->right = mergeTrees(root1->right, root2->right);
        
        return node;
    }
};

// LEETCODE 617