Given an integer N, the task is to find the count of N-digit numbers with all distinct digits.
Input: N = 1
1, 2, 3, 4, 5, 6, 7, 8 and 9 are the 1-digit numbers
with all distinct digits.
Input: N = 3
Approach: If N > 10 i.e. there will be atleast one digit which will be repeating hence for such cases the answer will be 0 else for the values of N = 1, 2, 3, …, 9, a series will be formed as 9, 81, 648, 4536, 27216, 136080, 544320, … whose Nth term will be 9 * 9! / (10 – N)!.
Below is the implementation of the above approach:
Time Complexity: O(n)
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- Numbers of Length N having digits A and B and whose sum of digits contain only digits A and B
- Minimum digits to be removed to make either all digits or alternating digits same
- Count numbers with exactly K non-zero digits and distinct odd digit sum
- Count of distinct numbers formed by shuffling the digits of a large number N
- Numbers with sum of digits equal to the sum of digits of its all prime factor
- Count of numbers between range having only non-zero digits whose sum of digits is N and number is divisible by M
- Count numbers in given range such that sum of even digits is greater than sum of odd digits
- Count of numbers upto N digits formed using digits 0 to K-1 without any adjacent 0s
- Numbers having Unique (or Distinct) digits
- Print a number strictly less than a given number such that all its digits are distinct.
- Count of distinct remainders when N is divided by all the numbers from the range [1, N]
- Check if the sum of digits of number is divisible by all of its digits
- Count of N-digit Numbers having Sum of even and odd positioned digits divisible by given numbers
- Count of integers in a range which have even number of odd digits and odd number of even digits
- Count numbers in range L-R that are divisible by all of its non-zero digits
- Count of all even numbers in the range [L, R] whose sum of digits is divisible by 3
- Count different numbers possible using all the digits their frequency times
- Count of numbers with all digits same in a given range
- Count all prime numbers in a given range whose sum of digits is also prime
- Count all N digit numbers whose digits are multiple of X
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