【剑指offer】【树】68-I.二叉搜索树的最近公共祖先

二叉搜索树的最近公共祖先

递归

/**
 * 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 -> 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);
        return root;
    }
};

迭代法

/**
 * 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(!root) return nullptr;
        while(root)
        {
            if(p -> val < root -> val && q -> val < root -> val) root = root -> left;
            else if(p -> val > root -> val && q -> val > root -> val) root = root -> right;
            else break;
        }
        return root;
    }
};

【剑指offer】【树】68-I.二叉搜索树的最近公共祖先

原文：https://www.cnblogs.com/Trevo/p/12683662.html