力扣-二叉树-235 二叉搜索树的最近公共祖先
思路
重点抓住二叉搜索树的特点是有序，然后思考清楚搜索到的p和q情况
class Solution {
public:
TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
if(root == NULL) return NULL;
if(root->val < p->val && root->val < q->val){
TreeNode* right = lowestCommonAncestor(root->right, p, q);
if(right != NULL) return right;
}else if(root->val > p->val && root->val > q->val){
TreeNode* left = lowestCommonAncestor(root->left, p, q);
if(left != NULL) return left;
}
return root;
}
};