LeetCode in Kotlin
357. Count Numbers with Unique Digits
Medium
Given an integer n, return the count of all numbers with unique digits, x, where 0 <= x < 10n.
Example 1:
Input: n = 2
Output: 91
Explanation: The answer should be the total numbers in the range of 0 ≤ x < 100, excluding 11,22,33,44,55,66,77,88,99
Example 2:
Input: n = 0
Output: 1
Constraints:
0 <= n <= 8
Solution
class Solution {
fun countNumbersWithUniqueDigits(n: Int): Int {
if (n == 0) return 1
var temp = 9
var res = 10
for (i in 1 until n) {
temp *= (10 - i)
res += temp
}
return res
}
}