Programming Challenge #3

August 6, 2008: Greetings, programmers! The 3rd DDP Programming Challenge has been opened before schedule. The challenge remains open until we receive a correct solution. Send your entries to:

prog.challenge@desdevpro.com

Don't forget to mention your name. Multiple entries will not be accepted.

August 6, 2008: We have a winner! The 2nd DesDevPro Programming Challenge has been won by

Tasnim Khan

Thank you all for the overwhelming response we got for the 2nd Challenge. We hope you keep up the enthusiasm. Among all the correct solutions recieved, we chose the one that was not only the earliest correct solution, but also used a very brief and precise logic. Heartiest congratulations to the winner! We have got in touch with the winner. Details about the winner will be on display on the winner page shortly. The 3rd Programming Challenge will be opened on Aug 7, 2008

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Problem Statement

The input for your program will be a string which may (or may not) conatain a '?' sign (a mark of interrogation).

Your program should first ignore the '?' and find out whether the string is a palindrome or not. If the string is not a palindrome, but contains a '?' then your program should find the letter(s) which must be inserted in the place of '?' to make the string a palindrome (if possible). Then the resulting palindrome and the filling letter should be displayed in the output, separated by a TAB space. The last line of the input will be a '#' which should not be processed. If more than one palindrome can be generated then each result should be followed by a single space, an ampersand (&), another space and then the next result.

SAMPLE INPUT

MADAM
BL?B
QWE?RTY
BB?
#

SAMPLE OUTPUT

MADAM <null>
BLLB L
<none>
BB <null> & BBB B

In the first output, since MADAM is already a palindrome, <null> is printed as the filling character. For the last input, there are two results, properly separated as directed above.

NOTE: You can assume that the input string will consist of only UPPERCASE letters apart from an optional ? sign. Only the last line will contain a # which should not be processed.

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Problems Archive

Programming Challenge #2

Programming Challenge #2 (Aug 1, 2008)

Winner: Tasneem Khan

Problem Statement

The digital root of a number is found by adding together the digits that make up the number. If the resulting number has more than one digit, the process is repeated until a single digit remains.
Your task in this problem is to calculate a variation on the digital root - a prime digital root. The addition process described above stops when there is only one digit left, but will also stop if the original number, or any of the intermediate numbers (formed by addition) are prime numbers. If the process continues and results in a single digit that is not a prime number, then the original number has no prime digital root.

An integer greater than one is called a prime number if its only positive divisors (factors) are one and itself.

For example, the first six primes are 2, 3, 5, 7, 11, and 13.
Number 6 has four positive divisors: 6, 3, 2, and 1. Thus number 6 is not a prime.
Caveat: number 1 is not a prime.

INPUT FORMAT

The input will contain a single integer on each line in the range 0 to 999999 inclusive.
The end of the input will be indicated by the value 0.

SAMPLE INPUT
1
3
4
11
642
128
886
0

OUTPUT FORMAT

If the input number has a prime digital root, then the input number must be output right aligned with a field width of 7. It must be followed by a single space, and then by the calculated prime digital root also right aligned with a field width of 7.
If the input number has no prime digital root, then the input number should be output as defined above followed by 4 spaces followed by the word none (in lowercase). The terminating zero should not be output.

SAMPLE OUTPUT

      1    none
      3       3
      4    none
     11      11
    642       3
    128      11
    886    none

Programming Challenge #1