## Algorithm

Problem Name: 235. Lowest Common Ancestor of a Binary Search Tree

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

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

Example 1:

```Input: root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 8
Output: 6
Explanation: The LCA of nodes 2 and 8 is 6.
```

Example 2:

```Input: root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 4
Output: 2
Explanation: The LCA of nodes 2 and 4 is 2, since a node can be a descendant of itself according to the LCA definition.
```

Example 3:

```Input: root = [2,1], p = 2, q = 1
Output: 2
```

Constraints:

• The number of nodes in the tree is in the range `[2, 105]`.
• `-109 <= Node.val <= 109`
• All `Node.val` are unique.
• `p != q`
• `p` and `q` will exist in the BST.

## Code Examples

### #1 Code Example with C Programming

```Code - C Programming```

``````
struct TreeNode* lowestCommonAncestor(struct TreeNode* root, struct TreeNode* p, struct TreeNode* q) {
if (root == NULL) {
return NULL;
}
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;
}
``````
Copy The Code &

Input

cmd
root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 8

Output

cmd
6

### #2 Code Example with C++ Programming

```Code - C++ Programming```

``````class Solution {
public:
TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
int Min = min(p->val, q->val);
int Max = max(p->val, q->val);
if(root->val  < = Max && root->val >= Min) return root;
if(root->val > Max) return lowestCommonAncestor(root->left, p, q);
return lowestCommonAncestor(root->right, p, q);
}
};
``````
Copy The Code &

Input

cmd
root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 8

Output

cmd
6

### #3 Code Example with Javascript Programming

```Code - Javascript Programming```

``````
const lowestCommonAncestor = function(root, p, q) {
while((root.val - p.val) * (root.val - q.val) > 0) {
root = root.val > p.val ? root.left : root.right
}
return root
};
``````
Copy The Code &

Input

cmd
root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 4

Output

cmd
2

### #4 Code Example with Python Programming

```Code - Python Programming```

``````
class Solution:
def lowestCommonAncestor(
self, root: "TreeNode", p: "TreeNode", q: "TreeNode"
) -> "TreeNode":
if p.val < root.val > q.val:
return self.lowestCommonAncestor(root.left, p, q)
if p.val > root.val < q.val:
return self.lowestCommonAncestor(root.right, p, q)
return root
``````
Copy The Code &

Input

cmd
root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 4

Output

cmd
2

### #5 Code Example with C# Programming

```Code - C# Programming```

``````
namespace LeetCode
{
public class _0235_LowestCommonAncestorOfABinarySearchTree
{
public TreeNode LowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q)
{
if (p.val > q.val) return LowestCommonAncestor(root, q, p);
if (root.val >= p.val && root.val  < = q.val) return root;
if (root.val < p.val && root.val < q.val) return LowestCommonAncestor(root.right, p, q);
else return LowestCommonAncestor(root.left, p, q);
}
}
}
``````
Copy The Code &

Input

cmd
root = [2,1], p = 2, q = 1

Output

cmd
2