Perl Weekly Challenge

HEADLINES

Colin Crain has been helping with Perl reviews since Week #065. I would like to thank him for all the hard work. I liked the new layout he came up for the last review. It is different from others. I am not sure about others but I always look forward to review every week. We are still looking for helping hands for Raku reviews. Please let us know perlweeklychallenge@yahoo.com if you have spare time to help us.

This week, I managed to do the live coding sessions for Week #068 and Week #069 in one sitting. It was tiring at the end but fun to watch my own video. Please find below the link to the videos.

Perl Weekly Challenge - 068 (Task #1)

Perl Weekly Challenge - 068 (Task #2)

Perl Weekly Challenge - 069 (Task #1)

Perl Weekly Challenge - 069 (Task #2)

If you want to check out past videos then please take a look at my YouTube Channel. Please do subscribe the channel if you don’t want to miss new videos.

Also don’t forget to watch the live coding session by Richard Park, the source of inspiration for me.

Last but not the least, I would like to thank each and every member for their support and encouragement.

RECAP

Quick recap of the “Perl Weekly Challenge - 069” by Mohammad S Anwar.

PERL REVIEW

Please checkout Perl solutions review of the “Perl Weekly Challenge - 068” by Colin Crain.

If you missed any past reviews then please checkout the collection.

RAKU REVIEW

If you missed any past reviews then please checkout the collection.

CHART

Please take a look at the charts showing interesting data.

I would like to thank every member of the team for their valuable suggestions. Please do share your experience with us.

NEW MEMBERS

We have a private Early Bird Club, whose members have the privilege to check out the weekly challenge before Monday, the launch day. Not only that they get more time to work on the tasks. Joining is very easy, just drop me a line at perlweeklychallenge@yahoo.com and you are good to go.

Please find out How to contribute?, if you have any doubts.

Please give it a try to an excellent tool EZPWC created by respected member Saif Ahmed of Team PWC.

GUESTS

Andrew Shitov shared solution to Task #2 in C++.

Richard Park shared solutions to Task #1 and Task #2 in APL.

Ulrich Rieke shared solution to Task #2 in C++.

Walt Mankowski shared solutions to Task #1 and Task #2 in C.

Walt Mankowski shared solutions to Task #1 and Task #2 in Python.

Please find out past solutions by respected guests. Please do share your creative solutions in other languages.

TASK #1 › Character Swapping

Submitted by: Mohammad S Anwar

You are given a string $S of size $N.

You are also given swap count $C and offset $O such that $C >= 1, $O >= 1, $C <= $O and $C + $O <= $N.

UPDATE: 2020-07-20 16:10:00

Pete Houston suggested to put additional constraint i.e. `$C <= $O`. He presented the use case `$S = 'abcd'`, `$C = 2`, `$O = 1`.

Write a script to perform character swapping like below:

$S[ 1 % $N ] <=> $S[ (1 + $O) % $N ]
$S[ 2 % $N ] <=> $S[ (2 + $O) % $N ]
$S[ 3 % $N ] <=> $S[ (3 + $O) % $N ]
...
...
$S[ $C % $N ] <=> $S[ ($C + $O) % $N ]

Example 1

Input:
    $S = 'perlandraku'
    $C = 3
    $O = 4

Character Swapping:
    swap 1: e <=> n = pnrlaedraku
    swap 2: r <=> d = pndlaerraku
    swap 3: l <=> r = pndraerlaku

Output:
    pndraerlaku

TASK #2 › Gray Code Sequence

Submitted by: Mohammad S Anwar

You are given an integer 2 <= $N <= 5.

Write a script to generate $N-bit gray code sequence.

2-bit Gray Code Sequence

[0, 1, 3, 2]

To generate the 3-bit Gray code sequence from the 2-bit Gray code sequence, follow the step below:

2-bit Gray Code sequence
[0, 1, 3, 2]

Binary form of the sequence
a) S1 = [00, 01, 11, 10]

Reverse of S1
b) S2 = [10, 11, 01, 00]

Prefix all entries of S1 with '0'
c) S1 = [000, 001, 011, 010]

Prefix all entries of S2 with '1'
d) S2 = [110, 111, 101, 100]

Concatenate S1 and S2 gives 3-bit Gray Code sequence
e) [000, 001, 011, 010, 110, 111, 101, 100]

3-bit Gray Code sequence
[0, 1, 3, 2, 6, 7, 5, 4]

Example

Input: $N = 4

Output: [0, 1, 3, 2, 6, 7, 5, 4, 12, 13, 15, 14, 10, 11, 9, 8]

Last date to submit the solution 23:59 (UK Time) Sunday 26th July 2020.