[刷题] 235 Lowest Common Ancestor of a Binary Search Tree

要求

• 给定一棵二分搜索树和两个节点，寻找这两个节点的最近公共祖先

示例

• 2和8的最近公共祖先是6
• 2和4的最近公共祖先是2

思路

• p q<node
• node<p q
• p<=node<=q

实现

 1 class Solution {
 2 public:
 3     TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
 4
 5         assert( p != NULL && q != NULL );
 6
 7         if( root == NULL )
 8             return NULL;
 9
10         if( p->val < root->val && q->val < root->val )
11             return lowestCommanAncestor( root->left , p , q );
12         if( p->val > root->val && q->val > root->val )
13             return lowestCommanAncestor( root->right , p , q );
14
15         return root;
16     }
17 };

相关

• 98 Validate Binary Search Tree
• 450 Delete Node in a BST
• 108 Convert Sorted Array to Binary Search Tree
• 230 Kth Smallest Element in a BST
• 236 Lowest Common Ancestor of a Binary Tree