题解 | #二叉搜索树的最近公共祖先#

/**
 * struct TreeNode {
 *  int val;
 *  struct TreeNode *left;
 *  struct TreeNode *right;
 *  TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 * };
 */
class Solution {
  public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param root TreeNode类
     * @param p int整型
     * @param q int整型
     * @return int整型
     */
    int lowestCommonAncestor(TreeNode* root, int p, int q) {
        // write code here
        if (!root) return -1;
        if ((p <= root->val && q >= root->val) || (p >= root->val && q <= root->val)) {
            return root->val;
        } else if (p <= root->val && q <= root->val)
            return lowestCommonAncestor(root->left, p, q);
        else {
            return lowestCommonAncestor(root->right, p, q);
        }
    }
};