Taeluf.com

part1

#!/usr/bin/env php
<?php
/**
 * 
 */

if (@$argv[1] == 'sample'){
    $input = file_get_contents(__DIR__.'/sample.txt');
} else {
    $input = file_get_contents(__DIR__.'/input.txt');
}

$lines = explode("\n", trim($input));
$expected_output = null;

# start with seeds:
    # 79 14 55 13
    # convert seeds into soil, using soil map:
# seed-to-soil map:
# 50 98 2
# 52 50 48
#
# Seed 79
# uses the 52 50 48 map bc that covers seed 50-97
# 52 - 50 = 2, so soil = seed(79) + 2 = 81
# soil is 81
#
# map_from:
#   map_to:
#       range_start
#       range_end
#       diff (amount to add to source)
#
# seed:
#   soil:
#       range_start: 98
#       range_end:   99
#       diff:        -48
#       ,
#       range_start: 50
#       range_end: 97
#       diff: 2 
#
# soil:
#   fertilizer ...
#
# Notes: 
# Seed 98 corresponds to soil 50
# Seed 98 corresponds to soil 51
#
# Seed 50 corresponds to soil 52
# Seed 51 corresponds to soil 53
# ...
# Seed 97 corresponds to soil 99



//
//
// Okay, then we have to parse it too

$seed_line = array_shift($lines);
$seed_line_parts = explode(": ", $seed_line);
$seed_numbers = explode(" ",trim($seed_line_parts[1]));

$maps_lines = trim(implode("\n", $lines));
$maps_texts = explode(":", $maps_lines);
$maps_texts = preg_split("/(:|\n\n)/", $maps_lines);

$key = null;

$map_texts = [];

foreach ($maps_texts as $index=>$map_text){
    if ($index%2===0){
        $map_parts = explode(" map",trim($map_text));
        $map_fromto = explode("-to-", $map_parts[0]);
        $from = $map_fromto[0];
        $to = $map_fromto[1];
        continue;
    }
    $map_texts[$from][$to] = $map_text;
    continue;
    $map_lines = explode("\n",trim($map_text));

}

$maps = [];

foreach ($map_texts as $from => $to_list){
    foreach ($to_list as $to => $map_text){
        
        $map_text_lines = explode("\n", $map_text);

        foreach ($map_text_lines as $line){
            $line = trim($line);
            if ($line=='')continue;
            $parts = explode(" ",$line);
            $range_start = (int)$parts[1];
            $range_end = $parts[2] + $range_start - 1;
            $diff = $range_start - $parts[0];
            $maps[$from][$to][] = 
                [
                    'range_start'=>$range_start,
                    'range_end'=>$range_end,
                    'diff'=>-1 * $diff, // add_to_source
                ];
        }
    }

}


function generate_outputs(string $input_name, int $input_value, array $maps){

    if (!isset($maps[$input_name])) return [];

    $outputs = [];
    foreach ($maps[$input_name] as $to => $map_list){
        foreach ($map_list as $index=>$map){
            if ($input_value >= $map['range_start']
                && $input_value <= $map['range_end']){
                $output = $input_value + $map['diff'];
                break 2;
            }
            $output = $input_value;
        }
    }

    //$outputs = [
        //$to => $output
    //];
    //$sub_outputs = ;
    $all_outputs = array_merge(
        [ $to => $output],
        generate_outputs($to, $output, $maps)
    );
        

    return $all_outputs;
}

$outputs = [];

foreach ($seed_numbers as $number){
    $outputs[$number] = generate_outputs('seed', $number, $maps);
}

$lowest_location = PHP_INT_MAX;
foreach ($outputs as $seed_number => $outputs){
    if ($outputs['location'] < $lowest_location)$lowest_location = $outputs['location'];
}

//print_r($outputs);

//print_r($maps);

echo "\n\nLowest location is: $lowest_location\n\n";