#!/usr/bin/perl
use constant VAL => 0;
use constant IDX => 1;
use constant SUM => 2;
use strict;
use warnings;

my @list1 = (1 .. 5);
my @list2 = (1 .. 5);

my @merge_list = map {[$_, 0, $_ + $list2[0]]} @list1; # Map over smaller list if known

while (@merge_list) {
    my ($min, $index) = ($merge_list[0][SUM], 0);    
    for (1 .. $#merge_list) {
        ($min, $index) = ($merge_list[$_][SUM], $_) if $merge_list[$_][SUM] < $min;
    }
    print "$min\n";
    $merge_list[$index][IDX]++;
    if ($merge_list[$index][IDX] > $#list2) {
        splice(@merge_list, $index, 1);
    }
    else {
        $merge_list[$index][SUM] = $merge_list[$index][VAL] + $list2[$merge_list[$index][IDX]];
    }
}