A number is non-decreasing if each of its digits is greater than or equal to the previous digit. For example, 223, 4455567, 899, are non-decreasing numbers.
Given an integer N, find the total number of non-decreasing numbers that have N digits.
Input: N = 1 Output: 10 Explaination: All the single digit numbers are non-decreasing. So count is 10.
Input: N = 2 Output: 55 Explaination: For number starting with 1 there is 1 decreasing number 10, for number starting with 2 there are 2 decreasing numbers. Similarly numbers starting with 3, 4 . . . 9 there are 3, 4 . . . 9 decreasing numbers. Total 45 decreasing numbers. Total possible numbers are 102 = 100. So total number of non-decreasing numbers are 100-45 = 55.
You do not need to read input or print anything. Your task is to complete the function count() which takes the number N as input parameter and return the total number of non-decreasing numbers.
Expected Time Complexity: O(N)
Expected Auxiliary Space: O(N)
1 ≤ N ≤ 500
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