The Weekly Challenge: 397

TABLE OF CONTENTS

  1. HEADLINES

  2. SPONSOR

  3. RECAP

  4. PERL REVIEW

  5. RAKU REVIEW

  6. CHART

  7. NEW MEMBERS

  8. GUESTS

  9. TASK #1: Absent Smallest Positive

10. TASK #2: Binary Reflection

HEADLINES

Welcome to the Week #397 of The Weekly Challenge.

Thank you, Team PWC, for the big jump in the contributions last week.

Even I managed to share solutions to both task this time.

Below is my contributions to the Week #396.

[Task #1 - Perl]: source code

sub finishing_order($order, $friends) {
    my %f = map { $_ => 1 } @$friends;
    return [grep {  $f{$_} } @$order];
}

[Task #2 - Perl]: source code

sub trionic(@arr) {
    my $n = @arr;
    return 'false' if $n < 4;

    my $i = 0;
    $i++ while $i < $n - 1 && $arr[$i] < $arr[$i + 1];
    my $p = $i;
    return 'false' if $p == 0;

    $i++ while $i < $n - 1 && $arr[$i] > $arr[$i + 1];
    my $q = $i;

    return 'false' if $q == $p || $q >= $n - 1;

    $i++ while $i < $n - 1 && $arr[$i] < $arr[$i + 1];

    return $i == $n - 1 ? 'true' : 'false';
}

[Task #1 - Raku]: source code

sub finishing-order(@order, @friends) {
    my %f = @friends.map({ $_ => True });
    return [ @order.grep({ %f{$_} }) ];
}

[Task #2 - Raku]: source code

sub trionic(*@arr) {
    my $n = @arr.elems;
    return 'false' if $n < 4;

    my $i = 0;
    $i++ while $i < $n - 1 && @arr[$i] < @arr[$i + 1];
    my $p = $i;
    return 'false' if $p == 0;

    $i++ while $i < $n - 1 && @arr[$i] > @arr[$i + 1];
    my $q = $i;

    return 'false' if $q == $p || $q >= $n - 1;

    $i++ while $i < $n - 1 && @arr[$i] < @arr[$i + 1];

    return $i == $n - 1 ?? 'true' !! 'false';
}

[Task #1 - Python]: source code

def finishing_order(order, friends):
    f = set(friends)
    return [x for x in order if x in f]

[Task #2 - Python]: source code

def trionic(arr):
    n = len(arr)
    if n < 4:
        return 'false'

    i = 0
    while i < n - 1 and arr[i] < arr[i + 1]:
        i += 1
    p = i
    if p == 0:
        return 'false'

    while i < n - 1 and arr[i] > arr[i + 1]:
        i += 1
    q = i

    if q == p or q >= n - 1:
        return 'false'

    while i < n - 1 and arr[i] < arr[i + 1]:
        i += 1

    return 'true' if i == n - 1 else 'false'

Thank you Team PWC, once again.

Happy Hacking!!

Last 5 weeks mainstream contribution stats. Thank you Team PWC for your support and encouragements.

Last 5 weeks guest contribution stats. Thank you each and every guest contributors for your time and efforts.

TOP 10 Guest Languages

Do you see your favourite language in the Top #10? If not then why not contribute regularly and make it to the top.

 1. Python     (4689)
 2. Rust       (1251)
 3. C          (1079)
 4. Haskell    (971)
 5. Ruby       (954)
 6. Lua        (938)
 7. C++        (762)
 8. Go         (733)
 9. JavaScript (662)
10. Java       (532)

Blogs with Creative Title

1. Trionic Finish by Arne Sommer.

2. Finishing Order, Trionic Array by Bob Lied.

3. Shaped Finishing by Jorg Sommrey.

4. What do I get out of this? by Packy Anderson.

5. A race and some hills by Peter Campbell Smith.

6. Trionic Finishing by Roger Bell_West.

GitHub Repository Stats

1. Commits: 51,810 (+85)

2. Pull Requests: 14,865 (+30)

3. Contributors: 281

4. Fork: 353

5. Stars: 221

SPONSOR

With start of Week #355, we have a new sponsor Marc Perry until the end of year 2026. Having said we are looking for more sponsors so that we can go back to weekly winner. If anyone interested please get in touch with us at perlweeklychallenge@yahoo.com. Thanks for your support in advance. You can find more informations here.

RECAP

Quick recap of The Weekly Challenge - 396 by Mohammad Sajid Anwar.

PERL REVIEW

If you missed any past reviews then please check out the collection.

RAKU REVIEW

If you missed any past reviews then please check out 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

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

Please try the excellent tool EZPWC created by respected member Saif Ahmed of Team PWC.

GUESTS

Please check out the guest contributions for the Week #396.

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

Task 1: Absent Smallest Positive

Submitted by: Mohammad Sajid Anwar

You are given an array of integers.

Write a script to return the smallest absent positive integer such that it is strictly greater than the average of all elements in the given array.

Example 1

Input: @arr = (1, 2, 4, 5, 6)
Output: 7

Average: (1 + 2 + 4 + 5 + 6) / 5 = 3.6
We need the smallest positive integer absent from nums that is strictly greater than 3.6.
The positive integers greater than 3.6 are 4, 5, 6, 7, ....

4 is in the given array.
5 is in the given array.
6 is in the given array.
7 is not in.

Example 2

Input: @arr = (-5, -2, -1, 3)
Output: 1

Average: (-5 -2 -1 + 3) / 4 = -1.25
We need the smallest absent positive integer strictly greater than -1.25.
Positive integers are 1, 2, 3, 4, ... (all are strictly greater than -1.25).

1 is positive and absent from the given array.

Example 3

Input: @arr = (1, 2, 3)
Output: 4

Average: (1 + 2 + 3) / 3 = 2.0
We need an integer strictly greater than 2.0.

3 is in the given array.
4 is not in.

Example 4

Input: @arr = (2, 3, 7, 8)
Output: 6

Average: (2 + 3 + 7 + 8) / 4 = 5.0
We need an integer strictly greater than 5.0.

6 is not in the given array.

Example 5

Input: @arr = (1, 1, 1, 10)
Output: 4

Average: (1 + 1 + 1 + 10) / 4 = 3.25
Positive integers strictly greater than 3.25: 4, 5, 6, ...

4 is not in the given array.

Task 2: Binary Reflection

Submitted by: Mohammad Sajid Anwar

You are given an array of integer.

Write a script to sort the given array in ascending order based on the binary reflection of each element. If two different numbers have the same binary reflection, the smaller original number should appear first.

Example 1

Input: @arr = (3, 6, 12)
Output: (3, 6, 12)

Decimal 3  = Binary 11 -> reverse is also same 11 = Decimal 3
Decimal 6  = Binary 110 -> reverse 011 = Decimal 3
Decimal 12 = Binary 1100 -> 0011 = Decimal 3

All three elements have the same binary reflection (3).
Since they tie, they are sorted by their original values in ascending order: (3, 6, 12).

Example 2

Input: @arr = (1, 2, 4, 8)
Output: (1, 2, 4, 8)

Decimal 1 = Binary 1 -> reverse is also same 1 = Decimal 1
Decimal 2 = Binary 10 -> reverse is 01 = Decimal 1
Decimal 4 = Binary 100 -> reverse 001 = Decimal 1
Decimal 8 = Binary 1000 -> reverse is 0001 = Decimal 1

All elements reflect to 1. Tie-breaking by original value yields (1, 2, 4, 8).

Example 3

Input: @arr = (7, 8, 9, 10)
Output: (8, 10, 7, 9)

Decimal 8  = Binary 1000 -> reverse 0001 = Decimal 1
Decimal 9  = Binary 1001 -> reverse 1001 = Decimal 9
Decimal 10 = Binary 1010 -> reverse 0101 = Decimal 5
Decimal 7  = Binary 111 -> reverse 111 = Decimal 7

Binary reflections:
8  -> 1
9  -> 9
10 -> 5
7  -> 7

Sorting by reflection values (1, 5, 7, 9) gives original elements (8, 10, 7, 9).

Example 4

Input: @arr = (5, 9, 15, 17)
Output: (5, 9, 15, 17)

Decimal 5  = Binary 101 -> reverse 101 = Decimal 5
Decimal 9  = Binary 1001 -> reverse 1001 = Decimal 9
Decimal 15 = Binary 1111 -> reverse 1111 = Decimal 15
Decimal 17 = Binary 10001 -> reverse 10001 = Decimal 17

All numbers are binary palindromes, so their reflections match their original decimal values (5, 9, 15, 17),
leaving the array order unchanged.

Example 5

Input: @arr = (11, 13, 14, 19)
Output: (14, 13, 11, 19)

Decimal 11 = Binary 1011 -> reverse 1101 = Decimal 13
Decimal 13 = Binary 1101 -> reverse 1011 = Decimal 11
Decimal 14 = Binary 1110 -> reverse 0111 = Decimal 7
Decimal 19 = Binary 10011 -> reverse 11001 = Decimal 25

Reflections:
14 -> 7
13 -> 11
11 -> 13
19 -> 25

Sorted by reflection values (7, 11, 13, 25) yields (14, 13, 11, 19).

By submitting a response to the challenge you agree that your name or pseudonym, any photograph you supply and any other personal information contained in your submission may be published on this website and the associated mobile app. Last date to submit the solution 23:59 (UK Time) Sunday 1st November 2026.