PWC 302

_posts/2025-01-05-PerlWeeklyChallenge302.md

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+---
+layout: post
+title:  "Perl Weekly Challenge 302: first challenge of the year"
+author: Luca Ferrari
+tags:
+- raku
+- perlweeklychallenge
+- perl
+- python
+- java
+permalink: /:year/:month/:day/:title.html
+---
+My personal solutions to the Perl Weekly Challenge.
+
+# Perl Weekly Challenge 302: first challenge of the year
+
+This post presents my solutions to the [Perl Weekly Challenge 302](https://perlweeklychallenge.org/blog/perl-weekly-challenge-302/){:target="_blank"}.
+<br/>
+I keep doing the Perl Weekly Challenge in order to mantain my coding skills in good shape, as well as in order to learn new things, with particular regard to Raku, a language that I love.
+<br/>
+This week, I solved the following tasks:
+
+<br/>
+- [PWC 302 - Task 1 - Raku](#task1)
+- [PWC 302 - Task 2 - Raku](#task2)
+
+# Raku Implementations
+
+<a name="task1"></a>
+## PWC 302 - Task 1 - Raku Implementation
+
+Given a set of binary strings and a number `x` of `1`s and `y` of `0`s, find out the largest size of a subset so that there are no more `$x` and `$y` conditions.
+
+
+
+<br/>
+<br/>
+```raku
+sub MAIN( Int :$x, Int :$y, *@str ) {
+
+    my %solutions;
+
+    for @str.permutations -> $array {
+		my @current-set;
+
+		for $array.Array -> $_ {
+
+		    if ( @current-set.join.grep( * ~~ 0 ).elems <= $y
+				&& @current-set.join.grep( * ~~ 1 ).elems <= $x ) {
+				@current-set.push: $_;
+		    }
+		    else {
+				last;
+		    }
+
+		}
+
+		%solutions{ @current-set.elems }.push: @current-set if ( @current-set );
+    }
+
+    %solutions.keys.max.say;
+}
+
+```
+<br/>
+<br/>
+
+The idea is quite simple: I iterate over all possible permutations of the array of binary strings, and build an array of element (strings) named `@current-set`. Every time I add a new string from the current permutation, I ensure that the `$x` and `$y` conditions are met, and once they are not met anymore I add the solution to the `%solutions` hash, keyed by the length of the subset.
+
+Therefore, it does suffice to grab the highest key.
+
+
+
+<a name="task2"></a>
+## PWC 302 - Task 2 - Raku Implementation
+
+
+Given an array of integers, find out a minimum start so that the sum of each step is greater than one.
+
+
+<br/>
+<br/>
+```raku
+sub MAIN() {
+
+    my @nums = -3, 2, -3, 2, 4;
+    for 0 .. Inf -> $start {
+		my $current = $start;
+		my $ok = True;
+
+		for @nums {
+		    $current += $_;
+		    if ( $current < 1 ) {
+				$ok = False;
+				last;
+		    }
+		}
+
+		$start.say and exit if ( $ok );
+    }
+}
+
+```
+<br/>
+<br/>
+
+I iterate on every possible number, and fo each value assumed as a start, I iterate over the array to ensure there is no step less than 1.
+At the first value that ensures me the condition, I print it and terminate the program.