<?php
$input_file = '../inputs/day1.txt';
if (file_exists($input_file)) {
	$input = file_get_contents($input_file);
	if ($input != null) {
		$nums = array_map(fn ($str) => (int)$str, array_filter(explode("\n", $input), 'is_numeric'));
		print 'Part 1 answer: ' . solve_part_one($nums) . "\n";
		print 'Part 2 answer: ' . solve_part_two($nums) . "\n";
	}
}

function solve_part_one(array $nums): int
{
	for ($i = 0; $i < count($nums); $i++) {
		for ($j = 0; $j < count($nums); $j++) {
			if ($nums[$i] + $nums[$j] == 2020) {
				return $nums[$i] * $nums[$j];
			}
		}
	}

	return 0;
}

function solve_part_two(array $nums): int
{
	for ($i = 0; $i < count($nums); $i++) {
		for ($j = 0; $j < count($nums); $j++) {
			for ($k = 0; $k < count($nums); $k++) {
				if ($nums[$i] + $nums[$j] + $nums[$k] == 2020) {
					return $nums[$i] * $nums[$j] * $nums[$k];
				}
			}
		}
	}

	return 0;
}