6174 is the Kaprekar constant. All natural numbers less than 10,000 (except some with same digits) can be reduced to 6174 in the following steps:
Order the digits of the number in descending and ascending order and compute the difference. Repeat the process till you get 6174.
Example
n = 2376
Digits in descending order = 7632
Digits in ascending order = 2367
Step1:
>> 7632 - 2367
ans = 5265
Step 2:
>> 6552 - 2556
ans = 3996
Step3:
>> 9963 - 3699
ans = 6264
Step4
>> 6642 - 2466
ans = 4176
Step5
>> 7641 - 1467
ans = 6174
Total number of steps = 5.
Your function should return the number of Kaprekar steps for a given input. Numbers such as 2222 will end in zero. These numbers will never result in 6174. They should return Inf.
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The behavior at x=6174 is artifically set to 0, which taints the pure-recursive 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 3000-0003=2997, 9972-2799=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 4-digit integer. Here is an example:
x = 1:
1000-0001 = 999
9990-0999 = 8991
9981-1899 = 8082
8820-0288 = 8532
8532-2358 = 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 1000-0001. the second iteration should be 9990-0999. for the problem as stated, the test suite gives solutions that are incorrect.
Quite interesting!
interesting problem