Lowest Common Ancestor of a Binary Search Tree

PROBLEM :

Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.

According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes v and w as the lowest node in T that has both v and w as descendants (where we allow a node to be a descendant of itself).”

             ___6___
           /               \
      _2_              _8_
     /      \           /      \
   0        4       7       9
            /  \
           3   5
For example, the lowest common ancestor (LCA) of nodes 2 and 8 is 6. Another example is LCA of nodes 2 and 4 is 2, since a node can be a descendant of itself according to the LCA definition.

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SIMPLE c++ IMPLEMENTATION :
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/**
 * 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==NULL)
        return root ;
     
    if(root->val>p->val&&root->val>q->val)
        return(lowestCommonAncestor(root->left,p,q)) ;
     
    if(root->val<p->val&&root->val<q->val)
        return(lowestCommonAncestor(root->right,p,q)) ;
     
    return root ;
 
}


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