Problem

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

Pre analysis

Will make use of BST info and trim sides if value is not in range