# Hip To Be Square: Perl Weekly Challenge #116

Listening to the starting talks of Conference in the Cloud 2021 while writing up my solutions to Perl Weekly Challenge #116

## TASK #1 › Number Sequence

Submitted by: Mohammad S Anwar

You are given a number`$N >= 10`

.Write a script to split the given number such that the difference between two consecutive numbers is always 1 and it shouldn’t have leading 0.

Print the given number if it impossible to split the number.

**This Looks Like A Job For Recursion!**

One of the examples is `1234`

, which can become

```
1,2,3,4
1,2,34
1,23,4
1,234
12,3,4
12,34
123,4
```

We go forward by using `substr`

to add commas, avoiding coma prefixes and suffixes, double commas and `,0`

, giving a prefix zero that will go away. When coding, I forgot that you can add a comma with `substr( $var, $position, 0 ) = ','`

so I went the long way. Oh well.

### Show Me The Code!

```
#!/usr/bin/env perl
use strict;
use warnings;
use feature qw{ postderef say signatures state };
no warnings qw{ experimental };
my @numbers = qw{ 1234 91011 10203 };
for my $n (@numbers) {
say base($n);
}
# we are asked to return the sequence
# or the given number, and accounting
# for that makes recursion difficult,
# so we pass to base to determine that
sub base ( $n ) {
my $s = get_sequence($n);
return $s//$n;
}
# test for success and return if successful
# then add commas within (a copy of) the
# string
sub get_sequence ( $n ) {
my $t = test($n);
return $n if $t;
my $output;
my @n = split /,/, $n;
my $flag = 0;
map { $flag += 1 if $_ > 10 } @n;
if ( $flag > 0 ) {
for my $i ( 0 .. length $n ) {
my $cp = $n;
my $l = substr( $cp, $i, 1 );
substr( $cp, $i, 1 ) = ',' . $l;
next if $cp =~ m{^\,|\,\,|\,$};
my $x = get_sequence($cp);
return $x if $x;
}
}
return undef;
}
sub test ( $n ) {
my $t = 1;
my @n = split /,/, $n;
$t = 0 if $n[0] =~ m{^0}mx;
$t = 0 if scalar @n < 2;
for my $i ( 1 .. -1 + scalar @n ) {
my $h = $i - 1;
$t = 0 if $n[$i] =~ m{^0}mx;
$t = 0 unless $n[$h] + 1 == $n[$i];
}
return $t;
}
```

```
PS C:\Users\jacob\Documents\GitHub\perlweeklychallenge-club\challenge-116\dave-jacoby\perl> .\ch-1.pl
1,2,3,4
9,10,11
10203
```

## TASK #2 › Sum of Squares

Submitted by: Mohammad Meraj Zia

You are given a number`$N >= 10`

.Write a script to find out if the given number

`$N`

is such that sum of squares of all digits is a perfect square. Print 1 if it is otherwise 0.

Stage 1: use `map`

to turn each member of the list of numbers to it’s square, then `sum0`

to add them all together.

Stage 2: use `sqrt`

to find the square root of the sum.

Stage 3: compare the result to a converted-to-integer version of itself to the plain result, to see if they’re the same, because *every number* has a square root that can be represented in floating point. And then, finally, a good-old ternary operator.

### Show Me The Code!

```
#!/usr/bin/env perl
use strict;
use warnings;
use feature qw{ postderef say signatures state };
no warnings qw{ experimental };
use List::Util qw{sum0};
my @numbers = sort (34, 50, 52, 10 );
for my $n ( @numbers ) {
my $b = sum_of_squares($n);
say join "\t", $n,$b?'Yes':'No';
}
sub sum_of_squares ( $n ) {
my $sum = sum0 map { $_ ** 2 } split //, $n;
my $root = sqrt $sum;
return int $root == $root ? 1 : 0 ;
}
```

```
PS C:\Users\jacob\Documents\GitHub\perlweeklychallenge-club\challenge-116\dave-jacoby\perl> .\ch-2.pl
10 Yes
34 Yes
50 Yes
52 No
```