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
|
#!/usr/local/bin/perl
use strict;
use warnings;
use feature qw(say);
use Test::More;
use Benchmark qw(cmpthese timethis);
use Data::Dumper qw(Dumper);
my @TESTS = (
[ [ [10,20],[20,20],[20,10],[10,10] ], 1 ],
[ [ [12,24],[16,10],[20,12],[18,16] ], 0 ],
[ [ [-2,5],[2,-5],[5,2],[-5,-2] ], 1 ],
[ [ [0,1],[1,0],[0,-1],[-1,0] ], 1 ],
);
is( is_square(@{$_->[0]}), $_->[1] ) foreach @TESTS;
done_testing();
sub is_square {
my @pts = @_;
## If we measure the squared distances between each
## pari of points of a square we get two distances -
## the edge and diagonal.
## The latter being twice the former...
##
## No other combination of points has this property.
## Compute distances...
my %D;
while(@pts>1) {
my $a = shift @pts;
$D{($a->[0]-$_->[0])**2+($a->[1]-$_->[1])**2}++ foreach @pts;
}
my %F = reverse %D;
return exists $F{2} && exists $F{4} && $F{2} == 2*$F{4} || 0;
}
|
