Week 138 Task 2

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+#!/usr/bin/perl
+# The Weekly Challenge 138
+# Task 2 Split Number
+# Usage: ch-2.pl $N
+use v5.12.0;
+use warnings;
+use List::Util qw/ any sum /;
+use Integer::Partition;
+use Algorithm::Combinatorics qw / permutations /;
+use Test::More tests => 3;
+
+my $NUM = $ARGV[0] || 1;
+
+say split_number($NUM);
+
+
+
+sub split_number {
+    my $N = $_[0];
+    my $rt = sqrt $N;
+    die "Input must be a square number\n" unless $rt == int $rt;
+    my $len = length $N;
+    my $upper = length $rt;
+
+    my %wlen;
+
+
+    my $i = Integer::Partition->new($len);
+    while (my $a = $i->next) {
+        next if any { $_ > $upper } @$a;
+        my $j = permutations($a);
+        while (my $b = $j->next) {
+            if (!defined($wlen{join ",", @$b})) {
+                my @config = ( substr($N ,0, $b->[0]) );
+                my $acc = 0;
+                for my $k (0..scalar @$b - 2) {
+                    $acc += $b->[$k];
+                    my $temp = substr($N, $acc, $b->[$k+1]);
+                    $temp =~ s/^[0]*//g;
+                    $temp = 0 if $temp eq "";
+                    push @config, $temp;
+                }
+                if ( (sum @config) == $rt) {
+                    say "sqrt($N) = " , 
+                        "$rt = ", 
+                        join " + ", map { $_ == 0 ? "(0)" : $_ } @config;
+                    return 1;
+                }
+                $wlen{join ",", @$b} = 1;
+            }
+        }
+    }
+
+    return 0;
+}
+
+ok split_number(81) == 1, "Example 1";
+ok split_number(9801) == 1, "Example 2";
+ok split_number(36) == 0, "Example 3";
+
+
+=pod for fun
+for my $num (1..100) {
+    split_number($num*$num);
+}
+
+Output:
+sqrt(1) = 1 = 1
+sqrt(81) = 9 = 8 + 1
+sqrt(100) = 10 = 10 + 0
+sqrt(1296) = 36 = 1 + 29 + 6
+sqrt(2025) = 45 = 20 + 25
+sqrt(3025) = 55 = 30 + 25
+sqrt(6724) = 82 = 6 + 72 + 4
+sqrt(8281) = 91 = 82 + 8 + 1
+sqrt(9801) = 99 = 98 + 01
+sqrt(10000) = 100 = 100 + 00
+