An undulating number is a number that has only two types of digits and alternate digits are same, i.e., it is of the form “ababab….”. It is sometimes restricted to non-trivial undulating numbers which are required to have at least 3 digits and a is not equal to b.
The first few such numbers are: 101, 121, 131, 141, 151, 161, 171, 181, 191, 202, 212, 232, 242, 252, 262, 272, 282, 292, 303, 313, 323, 343, 353, 363, 373, 383, 393, 404, 414, 424, 434, 454, 464, 474, 484, 494, …
Some higher undulating numbers are: 6363, 80808, 1717171.
- For any n >= 3, there are 9 × 9 = 81 non-trivial n-digit undulating numbers, since the first digit can have 9 values (it cannot be 0), and the second digit can have 9 values when it must be different from the first.
Given a number, check if it is Undulating numbers considering the definition of alternating digits, at least 3 digits and adjacent digits not same.
Input : n = 121 Output : Yes Input : n = 1991 Output : No
- Numbers less than N which are product of exactly two distinct prime numbers
- Print N lines of 4 numbers such that every pair among 4 numbers has a GCD K
- Count numbers which are divisible by all the numbers from 2 to 10
- Maximum sum of distinct numbers such that LCM of these numbers is N
- Count numbers which can be constructed using two numbers
- Absolute difference between the Product of Non-Prime numbers and Prime numbers of an Array
- Absolute Difference between the Sum of Non-Prime numbers and Prime numbers of an Array
- Print numbers such that no two consecutive numbers are co-prime and every three consecutive numbers are co-prime
- Sum of first n even numbers
- Add two numbers using ++ and/or --
- Taxicab Numbers
- Betrothed numbers
- LCM of N numbers modulo M
- Sum of all even numbers in range L and R
- Happy Numbers
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