/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 * };
 */
/**
 * 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
 *
 * 
 * @param t1 TreeNode类 
 * @param t2 TreeNode类 
 * @return TreeNode类
 */




struct TreeNode* mergeTrees(struct TreeNode* t1, struct TreeNode* t2 ) {
    // write code here
    if(t1 == NULL) return t2;
    if(t2 == NULL) return t1;
    t1->val += t2->val;
    
    t1->left = mergeTrees(t1->left, t2->left);
    t1->right = mergeTrees(t1->right, t2->right);

    return t1;
}