https://leetcode.com/problems/trim-a-binary-search-tree/
Given a binary search tree and the lowest and highest boundaries as L and R, trim the tree so that all its elements lies in [L, R] (R >= L). You might need to change the root of the tree, so the result should return the new root of the trimmed binary search tree.
Example 1:
Input:
1
/
0 2
L = 1
R = 2
Output:
1
2
Example 2:
Input:
3
/
0 4
2
/
1
L = 1
R = 3
Output:
3
/
2
/
1
代码：
/**
* 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* trimBST(TreeNode* root, int L, int R) {
if(!root) return NULL;
if(root -> val < L)
return trimBST(root -> right, L, R);
if(root -> val > R)
return trimBST(root -> left, L, R);
root -> left = trimBST(root -> left, L, R);
root -> right = trimBST(root -> right, L, R);
return root;
}
};
今天最后一道题 全世界晚安啦