153 lines
3.4 KiB
Perl
153 lines
3.4 KiB
Perl
#!/usr/bin/perl
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use v5.40;
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sub day1_1( $filename ) {
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open my $fh, '<', $filename;
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my @list1;
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my @list2;
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my $counter = 0;
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while(my $line = readline $fh) {
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my @data = split " ", $line;
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if (@data == 2) {
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push @list1, $data[0];
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push @list2, $data[1];
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} else {
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print "More than two data points found at: $counter\n";
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return -1;
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}
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$counter++;
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}
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@list1 = sort @list1;
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@list2 = sort @list2;
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if (@list1 != @list2) {
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print("indices don't match\n");
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return -1;
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}
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my $total = 0;
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foreach my $i ( 0 .. $#list1) {
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$total += abs($list1[$i] - $list2[$i]);
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}
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close $fh;
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return $total;
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}
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sub find_count($item, $is_sorted, @list) {
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if($is_sorted != 1) {
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@list = sort @list;
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}
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my $lower_bound = 0;
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my $upper_bound = $#list;
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my $index = 0;
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my $found_location = 0;
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until($found_location == 1) {
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if ($upper_bound - $lower_bound <= 1) {
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if ($list[$upper_bound] == $item) {
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$index = $upper_bound;
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last;
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} elsif ($list[$lower_bound] == $item) {
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$index = $lower_bound;
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last;
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} else {
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return 0;
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}
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}
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$index = round(($upper_bound + $lower_bound) / 2);
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if ($list[$index] > $item) {
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$upper_bound = $index;
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} elsif ($list[$index] < $item) {
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$lower_bound = $index;
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} else {
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last;
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}
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}
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my $count = 1;
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my $index_above = $index + 1;
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my $index_lower = $index - 1;
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my $index_above_found = 1;
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my $index_lower_found = 1;
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while( $index_above_found == 1 || $index_lower_found == 1 ) {
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if($index_above_found == 1) {
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if($list[$index_above] == $item) {
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$count++;
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$index_above++;
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} else {
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$index_above_found = 0;
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}
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}
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if($index_lower_found == 1) {
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if($list[$index_lower] == $item) {
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$count++;
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$index_lower--;
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} else {
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$index_lower_found = 0;
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}
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}
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}
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return $count;
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}
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sub day1_2( $filename ) {
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open( my $FH, '<', $filename) or die $!;
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my @list1;
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my @list2;
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my $counter = 0;
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while(<$FH>) {
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my @data = split(" ", $_);
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if (@data == 2) {
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push(@list1, $data[0]);
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push(@list2, $data[1]);
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} else {
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print("More than two data points found at: $counter\n");
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return -1;
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}
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$counter++;
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}
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if($#list1 != $#list2) {
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print("indices don't match\n");
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return -1;
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}
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@list1 = sort @list1;
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@list2 = sort @list2;
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my $total = 0;
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my $prev_num = 0;
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my $prev_count = 0;
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foreach my $item (@list1) {
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my $loc_count = 0;
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if ($item == $prev_num ) {
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$loc_count = $prev_count;
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} else {
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$loc_count = find_count($item, 1, @list2);
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}
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$total += $item * $loc_count;
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$prev_num = $item;
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$prev_count = $loc_count;
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}
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return $total;
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}
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my $data = "./input_day_1_1.txt";
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my $sum = day1_1($data);
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my $simi = day1_2($data);
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print("Sum of differences: $sum\n");
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print("Similarity score: $simi\n");
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