//url:https://leetcode.com/problems/merge-two-binary-trees/description/

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    TreeNode* mergeTrees(TreeNode* t1, TreeNode* t2) {
        if(!t1)
            return t2;
        if(!t2)
            return t1;
        t1->val+=t2->val;
        t1->left=mergeTrees(t1->left,t2->left);
        t1->right=mergeTrees(t1->right,t2->right);
        return t1;
    }
      

};