用c 语言写一段二叉树合并的代码输入

两个二叉树的根节点，返回合并后的二叉树根节点。

struct TreeNode { int val; struct TreeNode *left; struct TreeNode *right; };

struct TreeNode* mergeTrees(struct TreeNode* t1, struct TreeNode* t2) { if (t1 == NULL) { return t2; } if (t2 == NULL) { return t1; } struct TreeNode* root = (struct TreeNode*)malloc(sizeof(struct TreeNode)); root->val = t1->val + t2->val; root->left = mergeTrees(t1->left, t2->left); root->right = mergeTrees(t1->right, t2->right); return root; }