#2376
Count Special Integers
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Description
We call a positive integer special if all of its digits are distinct.
Given a positive integer n, return the number of special integers that belong to the interval [1, n].
Example 1:
Input: n = 20
Output: 19
Explanation: All the integers from 1 to 20, except 11, are special. Thus, there are 19 special integers.
Example 2:
Input: n = 5
Output: 5
Explanation: All the integers from 1 to 5 are special.
Example 3:
Input: n = 135
Output: 110
Explanation: There are 110 integers from 1 to 135 that are special.
Some of the integers that are not special are: 22, 114, and 131.
Solution