LeetCode Lowest Common Ancestor of a Binary Search Tree

LeetCode Lowest Common Ancestor of a Binary Search Tree

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.

```class Solution {
public:
TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
if (p->val > q->val)swap(p, q);
if (p->val <= root->val&&q->val >= root->val)return root;
if (p->val < root->val&&q->val < root->val)return lowestCommonAncestor(root->left, p, q);
if (p->val > root->val&&q->val>root->val)return lowestCommonAncestor(root->right, p, q);
}
};
```