Lowest Commnon Ancestor

https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/?tab=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* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
        if(root == NULL || p == NULL || q == NULL)
        {
            return NULL;
        }

        if(p == root || q == root)
        {
            return root;
        }

        TreeNode* left = lowestCommonAncestor(root->left, p, q);
        TreeNode* right = lowestCommonAncestor(root->right, p, q);

        if(left != NULL && right != NULL)
        {
            return root;
        }

        if(left != NULL)
        {
            return left;
        }

        if(right != NULL)
        {
            return right;
        }

        return NULL;
    }
};