LeetCode 235 Lowest Common Ancestor of a Binary Search Tree

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
struct TreeNode* lowestCommonAncestor(struct TreeNode* root, struct TreeNode* p, struct TreeNode* q) {
    if(!root||!p||!q)
        return NULL;
    if(root->val < p->val && root->val < q->val)
        return lowestCommonAncestor(root->right,p,q);
    else if(root->val > p->val && root->val > q->val)
        return lowestCommonAncestor(root->left,p,q);
    else return root;
}