A number is called a stepping number if all adjacent digits have an absolute difference of 1, e.g. '321' is a Stepping Number while 421 is not. Given two integers n and m, find the count of all the stepping numbers in the range [n, m].
Example 1:
Input: n = 0, m = 21
Output: 13
Explanation: Stepping no's are 0 1 2 3 4 5
6 7 8 9 10 12 21
Example 2:
Input: n = 10, m = 15
Output: 2
Explanation: Stepping no's are 10, 12
Your Task:
You don't need to read input or print anything. Your task is to complete the function steppingNumbers() which takes the integer n and integer m as input parameters and returns the number of stepping numbers in the range between n and m.
Expected Time Complexity: O(log(M))
Expected Auxiliary Space: O(SN) where SN is the number of stepping numbers in the range
Constraints:
0 ≤ N < M ≤ 10^{7}

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