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
题目含义:给定一棵二叉搜索树和最小最大边界L
和R
,修剪这棵树,使得其中的元素位于L
和R
之间。
1 public TreeNode trimBST(TreeNode root, int L, int R) { 2 if (root == null) return null; 3 4 if (root.val < L) return trimBST(root.right, L, R); 5 if (root.val > R) return trimBST(root.left, L, R); 6 7 root.left = trimBST(root.left, L, R); 8 root.right = trimBST(root.right, L, R); 9 10 return root; 11 }