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
86
|
#!/usr/bin/env perl
# vim:set ts=4 sw=4 sts=4 et ai wm=0 nu:
#=============================================================================
# ch-1.pl Perl Weekly Challenge 241 Task 1 Arithmetic Triplets
#=============================================================================
# Copyright (c) 2023, Bob Lied
#=============================================================================
# You are given an array (3 or more members) of integers in increasing
# order and a positive integer. Write a script to find out the number
# of unique Arithmetic Triplets satisfying the following rules:
# a) i < j < k
# b) nums[j] - nums[i] == diff
# c) nums[k] - nums[j] == diff
# Example 1 Input: @nums = (0, 1, 4, 6, 7, 10) $diff = 3
# Output: 2
# Index (1, 2, 4) is an arithmetic triplet
# because both 7 - 4 == 3 and 4 - 1 == 3.
# Index (2, 4, 5) is an arithmetic triplet
# because both 10 - 7 == 3 and 7 - 4 == 3.
# Example 2 Input: @nums = (4, 5, 6, 7, 8, 9) $diff = 2
# Output: 2
# (0, 2, 4) is an arithmetic triplet with difference 2
# (1, 3, 5) is an arithmetic triplet with difference 2
#=============================================================================
use v5.38;
use Getopt::Long;
my $Verbose = 0;
my $DoTest = 0;
my $Diff;
GetOptions("diff:i" => \$Diff, "test" => \$DoTest, "verbose" => \$Verbose);
exit(!runTest()) if $DoTest;
die "Usage: $0 -d DIFF m n o ..." unless defined $Diff && @ARGV > 0;
say triplet($Diff, @ARGV);
sub triplet($diff, @nums)
{
my $count = 0;
my @show;
# for ( my $i = 0 ; $i <= $#nums-2; $i++ )
while ( defined(my $i = shift @nums ) )
{
for ( my $j = 0; $j <= $#nums-1; $j++ )
{
my $dj = $nums[$j] - $i;
# Input is sorted, so stop once the difference is too big.
last if $dj > $diff;
next unless $dj == $diff;
for ( my $k = $j+1; $k <= $#nums ; $k++ )
{
my $dk = $nums[$k] - $nums[$j];
last if $dk > $diff;
if ( $dk == $diff )
{
$count++;
push @show, [ $i, $j, $k ] if $Verbose;
}
}
}
}
if ( $Verbose )
{
for my $triplet ( @show )
{
say "\@nums[$triplet->@*] = ( @nums[$triplet->@*] )";
}
}
return $count;
}
sub runTest
{
use Test2::V0;
is( triplet(3, 0,1,4,6,7,10), 2, "Example 1");
is( triplet(2, 4,5,6,7,8,9 ), 2, "Example 2");
done_testing;
}
|
