Range in a Binary Search Tree

Given a binary search tree (BST) and two integers (L) and (R), your task is to find all the elements in the BST that lie in the inclusive range ([L, R]). The resulting elements should be returned in ascending order.

Note: The BST is provided as a level-order traversal where the value 'null' represents a missing node. For example, the BST
10 5 15 3 7 12 18
represents the tree:

10
/  

5    15
/ \   / 

3   7 12 18

If (L = 7) and (R = 15), then the expected output is 7 10 12 15.

inputFormat

Input is read from standard input (stdin). The first line contains the level-order traversal of the BST as space-separated values. Use the string "null" for missing nodes. The second line contains two space-separated integers (L) and (R), representing the lower and upper bounds of the range respectively.

outputFormat

Output the values within the range ([L, R]) in ascending order as a single line of space-separated integers, printed to standard output (stdout). If no values fall within the given range, output an empty line.## sample

10 5 15 3 7 12 18
7 15

7 10 12 15