function pairOfDoubles($str)
{
$letters = str_split($str);
foreach ($letters as $i => $letter) {
$strOfTwo = $letter . $letters[$i + 1];
$remainder = substr($str, $i + 2);
if (strpos($remainder, $strOfTwo) !== false) {
return true;
}
}
return false;
}
//repeating letters with another letter between
function repeatSandwich($str)
{
$letters = str_split($str);
foreach ($letters as $i => $letter) {
if (isset($letters[$i + 2]) && $letters[$i + 2] === $letter) {
return true;
}
}
return false;
}
$countOfNice = 0;
foreach ($strings as $string) {
if (isNice($string)) {
$countOfNice++;
}
}
echo $countOfNice;
return $countOfNice;
function processList($list)
{
$bits = explode("\n", $list);
$nice = 0;
foreach ($bits as $str) {
if (isNice($str)) {
$nice++;
}
}
echo "Nice is {$nice}\n";
}
<?php
/**
* Check if a string is naughty or nice
*
* @param string $string
* @return bool
*/
function isNice($string)
{
return preg_match('/([a-z]{2}).*?(\\1)/i', $string) && preg_match('/([a-z])[a-z](\\1)/i', $string);
// has repeating letters
}
$handle = fopen("input.txt", "r");
$niceStrings = 0;
if ($handle) {
while (($line = fgets($handle)) !== false) {
if (isNice($line)) {
$niceStrings++;
}
}
fclose($handle);
}
echo 'Total nice strings: ' . $niceStrings . PHP_EOL;
<?php
$niceStringCount = 0;
$input = fopen(__DIR__ . '/input', 'r');
while ($line = fgets($input)) {
$niceStringCount += (int) isNice($line);
}
fclose($input);
echo "Number of nice strings: {$niceStringCount}\n";
<?php
$input = file_get_contents("inputs/day5input.txt");
$i = 0;
foreach (explode("\n", $input) as $string) {
// Swap isNice to is2Nice for Part 2
if (isNice(strtolower($string))) {
$i = $i + 1;
}
}
echo $i;
// Part 1 helping functions
function isNice($string)
{
return hasRepeatLetters($string) && !hasExceptionStrings($string) && hasThreeVowels($string);
}
function hasRepeatLetters($string)
{
// Simple back reference should work here
// Not sure why the back reference needed escaping though
return preg_match("/([a-z])\\1/i", $string);
}
// This could have been done with a single regex string. Strpos is faster.
// I imagined Part 2 would have built on this so I made it easier to adapt.
// preg_match("/(ab|cd|pq|xy/", $string) would have been better.
function hasExceptionStrings($string)
{
$strings = ['ab', 'cd', 'pq', 'xy'];
foreach ($strings as $str) {
// This is faster than a preg_match
if (strpos($string, $str) !== false) {
