235.二叉搜索树的最近公共祖先

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 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).”

Given binary search tree:  root = [6,2,8,0,4,7,9,null,null,3,5]

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.

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/lowest-common-ancestor-of-a-binary-search-tree

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */

  class Solution {
  public:
      TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
          if (p==root||q==root)
              return root;

          if (p->val > root->val && q->val > root->val)
              return lowestCommonAncestor(root->right, p, q);
          else if (p->val < root->val && q->val < root->val)
              return lowestCommonAncestor(root->left, p, q);
          else
              return root;
      }
  };

感觉没学过C++，main函数里都不知道怎么调用、怎么定义这种数据结构类型的数组。

235.二叉搜索树的最近公共祖先

原文：https://www.cnblogs.com/solitude-cosmos/p/13737830.html