Practice Count Special Integers
Read the task, work through the examples, and check your approach against the constraints. Use the original LeetCode task for coding and submissions.
Problem Statement
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].
Source: Count Special Integers on LeetCode. Use the original task for its coding environment and submissions.
Examples
# Example 1
Input
n = 20
Output
19
# Example 2
Input
n = 5
Output
5
# Example 3
Input
n = 135
Output
110
Constraints
1 <= n <= 2 * 10^9
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