A stepping number is an integer such that all of its adjacent digits have an absolute difference of exactly 1.
321 is a stepping number while 421 is not.Given two integers low and high, return a sorted list of all the stepping numbers in the inclusive range [low, high].
Example 1:
Input: low = 0, high = 21 Output: [0,1,2,3,4,5,6,7,8,9,10,12,21]
Example 2:
Input: low = 10, high = 15 Output: [10,12]
Constraints:
0 <= low <= high <= 2 * 109