669. 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
给定一棵二叉搜索树,求去掉【L,R】范围外的结点后的二叉搜索树
C++(26ms):
/** * 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 == NULL) 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 ; } };