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].
Examples
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.
Constraints
1 <= n <= 2 * 109
2376. Count Special Integers
Hard
50 Points
Math
Dynamic Programming
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].
Examples
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.
Constraints
1 <= n <= 2 * 109
Count Special Integers - Practice Coding | SlaveCode