#!/usr/bin/perl
use warnings;
use strict;

sub avg_time {
    my ($s1, $s2) = @_;
    my ($t1, $t2) = map 60 * (split /:/)[0] + (split /:/)[1], $s1, $s2
+;
    my $avg = ($t1 + $t2) / 2;

    # The times are closer to each other via midnight than via noon.
    $avg += 12 * 60 if abs($t1 - $t2) > 12 * 60;

    # Don't report hours > 23.
    $avg %= 24 * 60;

    return join ':', map sprintf('%02d', $_), int $avg / 60, $avg % 60
}

use Test::More;
is avg_time('11:00', '13:00'), '12:00';
is avg_time('23:00', '01:00'), '00:00';
is avg_time('10:59', '13:01'), '12:00';
is avg_time('22:59', '01:01'), '00:00';
is avg_time('03:00', '21:00'), '00:00';
is avg_time('10:20', '22:10'), '16:15';
is avg_time('10:10', '22:20'), '04:15';

done_testing();
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Unlike GotToBTru, I don't think 7:00 - 9:00 should give different results to 9:00 - 7:00 (the "next day" tests with both times AM or PM). The other tests mentioned there pass.

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
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