Problem 68. Kaprekar Steps
Solution Stats
Problem Comments

18 Comments
The behavior at x=6174 is artifically set to 0, which taints the purerecursive solution, but hey it was cool problem!
The K constant is 495 for 3 digits.
So the test with 691 is wrong.
Why tests with only one digit ?
Did I miss something ?
I don't understand the Test Suite for x = 3 and x = 1 too. what should I do in this case?
For x=3, the steps are 30000003=2997, 99722799=7173, etc.
Problem description is confusing as there are different Kaprekar constants depending on the number of digits. [0 9 495 6174 for 1, 2,3 4 digits respectively.
getting this error:
Internal Server Error  Read
The server encountered an internal error or misconfiguration and was unable to complete your request.
Reference #3.c2c1ab8.1412090777.18623697
any ideas?
The problem should specify that any number with less than four digits should be filled up to four digits with leading zeros. (e.g. 3 > 0003)
Very nice and interesting problem!
I like the recursion aspect of this problem.
There is a small correction needed in the problem statement. Not all natural numbers, but 4 digit numbers can be reduced to Kaprekar number by the mentioned method. Similarly 3 digit numbers can be reduced to 495
https://en.wikipedia.org/wiki/D._R._Kaprekar
How it works x = 1？？？？？
For those confused with test cases 2,3 and 5, like myself before, do conversion to 4digit integer. Here is an example:
x = 1:
10000001 = 999
99900999 = 8991
99811899 = 8082
88200288 = 8532
85322358 = 6174
Therefore, y_correct = 5
love it!!!
Very nice. Took some few minutes to crack this.
What I did is to convert x into string and then use sort function.
nice problem
ATTENTION
This problem statement is poorly given and leaves out a crucial element the input number must always have 4 digits, so if 1 is the input, the first iteration should be 10000001. the second iteration should be 99900999. for the problem as stated, the test suite gives solutions that are incorrect.
Quite interesting!
interesting problem
Solution Comments
Show commentsProblem Recent Solvers2290
Suggested Problems

Find common elements in matrix rows
2628 Solvers

Project Euler: Problem 4, Palindromic numbers
1029 Solvers

Set the array elements whose value is 13 to 0
1362 Solvers

Spot the First Occurrence of 5
417 Solvers

645 Solvers
More from this Author96
Problem Tags
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!