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; } };