Stepping Numbers(LeetCode 1215):

Problem

A stepping number is an integer such that all of its adjacent digits have an absolute difference of exactly 1.

  • For example, 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