1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
|
#!/usr/bin/env perl
# vim:set ts=4 sw=4 sts=4 et ai wm=0 nu:
#=============================================================================
# Copyright (c) 2024, Bob Lied
#=============================================================================
#
# ch-1.pl Perl Weekly Challenge 252 Task 1 Special Numbers
#=============================================================================
# You are given an array of integers, @ints.
# Write a script to find the sum of the squares of all special elements of
# the given array. An element $int[i] of @ints is called special if
# i divides n, i.e. n % i == 0. Where n is the length of the given array.
# Also the array is 1-indexed for the task.
# Example 1 Input: @ints = (1, 2, 3, 4)
# Output: 21
# There are exactly 3 special elements in the given array:
# $ints[1] since 1 divides 4,
# $ints[2] since 2 divides 4, and
# $ints[4] since 4 divides 4.
# Hence, the sum of the squares of all special elements of given array:
# 1 * 1 + 2 * 2 + 4 * 4 = 21.
# Example 2 Input: @ints = (2, 7, 1, 19, 18, 3)
# Output: 63
#=============================================================================
use v5.38;
use builtin qw/true false/; no warnings "experimental::builtin";
use List::Util qw/sum0/;
use Getopt::Long;
my $Verbose = 0;
my $DoTest = 0;
GetOptions("test" => \$DoTest, "verbose" => \$Verbose);
exit(!runTest()) if $DoTest;
sub specialNumbers(@ints)
{
my $len = @ints;
# Insert an extra element at the front to make it 1-indexed
unshift @ints, $len+1;
return sum0 map { $_ * $_ } @ints[ grep { $len % $_ == 0 } 1 .. $len ];
}
sub factorsOf($n)
{
use List::Util qw/uniqint/;
my @flist = (1, $n);
for my $f ( 2 .. int(sqrt($n)) )
{
push @flist, ($f, $n/$f) if $n % $f == 0;
}
return [ uniqint sort { $a <=> $b } @flist ]
}
sub sn2(@ints)
{
use List::MoreUtils qw/before/;
my $len = @ints;
return 0 if $len == 0;
my @choose = map { $_ - 1 } before { $_ > $len } factorsOf($len)->@*;
return sum0 map { $_ * $_ } @ints[@choose];
}
sub runTest
{
use Test2::V0;
is( specialNumbers(1,2,3,4), 21, "Example 1");
is( specialNumbers(2,7,1,19,18,3), 63, "Example 2");
is( specialNumbers(8 ), 64, "Singleton");
is( specialNumbers() , 0, "Empty list");
is( sn2(1,2,3,4), 21, "sn2 Example 1");
is( sn2(2,7,1,19,18,3), 63, "sn2 Example 2");
is( sn2(8 ), 64, "sn2 Singleton");
is( sn2() , 0, "sn2 Empty list");
is( factorsOf( 6), [1,2,3,6], "factorsOf 6");
is( factorsOf(36), [1,2,3,4,6,9,12,18,36], "factorsOf 36");
done_testing;
}
|
