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#!/usr/bin/perl -s
use v5.16;
use Test2::V0 '!float';
use PDL;
our ($tests, $examples);
run_tests() if $tests || $examples; # does not return
die <<EOS unless @ARGV;
usage: $0 [-examples] [-tests] [--] [N...]
-examples
run the examples from the challenge
-tests
run some tests
N...
list of integers
EOS
### Input and Output
say count_max_gap(@ARGV);
### Implementation
# Sort the numbers, build pairs of adjacent values, take the differences
# of the pairs by flipping the sign of the second elements and summing
# over the pairs. Then count the elements having the maximum value.
sub count_max_gap {
return 0 unless @_ > 1;
my $gap = sumover long(@_)->qsort->lags(0, 1, 2)->xchg(0, 1) * long 1, -1;
$gap->where($gap == max $gap)->dim(0);
}
### Examples and tests
sub run_tests {
SKIP: {
skip "examples" unless $examples;
is count_max_gap(qw(2 5 8 1)), 2, 'example 1';
is count_max_gap(3), 0, 'example 2';
}
SKIP: {
skip "tests" unless $tests;
is count_max_gap(qw(8 6 4 3 2 1)), 2, 'max count not at max gap';
is count_max_gap(qw(3 3 3)), 2, 'zero gap';
is count_max_gap(qw(5 3 2 1)), 1, 'single max gap';
is count_max_gap(qw(1 2 3 -1)), 1, 'negative number in max gap';
is count_max_gap(2, 1), 1, 'single gap';
is count_max_gap(), 0, 'empty list';
}
done_testing;
exit;
}
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