Perl Weekly Challenge 114: palindrome and ‘1’s numbers

One way to let me improve my knowledge about Raku (aka Perl 6) is to implement programs in it. Unluckily, I don’t have any production code to implement in Raku yet (sob!). So, why not try solving the Perl Weekly Challenge tasks?

In the following, the assigned tasks for Challenge 114.

• Task 1
• Task 2

PWC 114 - Task 1

The first task was abount finding the next palindrome number greater thana given one.
It is a quite simple task to me: a number is palindrome if its flipped string representation is the same, so it all means I have to loop over numbers bigger than the current one and see if it is a palindrome.

sub MAIN( Int $N where { $N > 10 } ) {
    say $_ and exit  if $_ == $_.Str.flip.Int for $N ^.. Inf;
}

Therefore I loop from $N (exlcuded), i.e., the given number, to the infinity. For every number, $_, I compare it to its flipped version, and the if the numbers are the same, then I do print the value and exit.
Please note the lower precedence and in the say $_ and exit that avoid exit to take precedence on the whole thing and terminate the program without printing anything.

PWC 114 - Task 2

The second task was a kind of one liner too: find out a number that has the same amount of 1 digits in the binary representation, assuming it is bigger than a give value.

sub MAIN( Int $N where { $N > 0 } ) {
    say $_ and exit if ( $N.base( 2 ).split( '' ).grep( '1' ).elems
                              == $_.base( 2 ).split( '' ).grep( '1' ).elems )
                                  for $N ^.. Inf;

}

Again, I do loop from the given number to the infinity, and for every value I check if the number, converted into binary thru .base( 2 ), reduced to an array of digits by means of split( '' ), extracted to its only 1 digits by means of grep( '1' ) has the same number of elements of the current number.
In the case, I do print the value and terminate the script.
Of course, this is a concise approach, but is not optimized, since it computes over and over again the number of 1 digits of the given number $N.