## Question

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.

## Solution

**Result:** Accepted **Time:** 24 ms

Here should be some explanations.

```
/**
* 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(p->val > root-> val && q->val > root->val)
return lowestCommonAncestor(root->right,p,q);
if(p->val < root-> val && q->val < root->val)
return lowestCommonAncestor(root->left,p,q);
return root;
}
```

**Complexity Analytics**

- Time Complexity:
- Space Complexity: