Robbie Hatley's Solutions To The Weekly Challenge #258

For those not familiar with "The Weekly Challenge", it is a weekly programming puzzle with two parts, cycling every Sunday. You can find it here:

The Weekly Challenge

This week (2024-02-25 through 2024-03-02) is weekly challenge #258. Its tasks are as follows:

Task 258-1: Count Even Digits Number
Submitted by: Mohammad Sajid Anwar
You are given a array of positive integers, @ints. Write a script 
to find out how many integers have even number of digits.

Example 1:
Input: @ints = (10, 1, 111, 24, 1000)
Output: 3
There are 3 integers having even digits i.e. 10, 24 and 1000.

Example 2:
Input: @ints = (111, 1, 11111)
Output: 0

Example 3:
Input: @ints = (2, 8, 1024, 256)
Output: 1

I'm "traveling light" this week, so my solutions for 258-1 and 258-2 are about 50 times shorter than the programs I normally write for The Weekly Challenge. My solution for 258-1 is especially short; it uses "grep" to filter @ARGV for numbers with an even number of digits, then uses "scalar" to count them:

#!/usr/bin/perl
print scalar grep {0==length($_)%2} @ARGV, "\n";

Task 258-2: Sum of Values
Submitted by: Mohammad Sajid Anwar
You are given an array of integers, @int and an integer $k.
Write a script to find the sum of values whose index binary 
representation has exactly $k number of 1-bit set.

Example 1:
Input: @ints = (2, 5, 9, 11, 3), $k = 1
Output: 17
Binary representation of index 0 = 0
Binary representation of index 1 = 1
Binary representation of index 2 = 10
Binary representation of index 3 = 11
Binary representation of index 4 = 100
So the indices 1, 2 and 4 have total one 1-bit sets.
Therefore the sum, $ints[1] + $ints[2] + $ints[4] = 17

Example 2:
Input: @ints = (2, 5, 9, 11, 3), $k = 2
Output: 11

Example 3:
Input: @ints = (2, 5, 9, 11, 3), $k = 0
Output: 2

This one was a little more involved than task 1. First, I popped $k off the right end of @ARGV, then I used "grep" to grab just those values of index for which the sum of binary digits (which is also the number of "1" digits set) is equal to $k, then I used those indexes to "slice" @ARGV, then summed the slice:

#!/usr/bin/perl
use List::Util 'sum0';
my $k = pop @ARGV;
print sum0(@ARGV[grep {$k == sum0(split //, sprintf("%b", $_))} 0..$#ARGV]), "\n";

That's it for challenge 258; see you on challenge 259!