3rd and 2nd day

01/index.php

@@ -1,17 +0,0 @@
-<?php
-/**
- *
- */
-
-$increased = 0;
-$inputStream = fopen('input', 'r');
-$previousReading = (int)fgets($inputStream);
-while (($line = fgets($inputStream)) !== false) {
-    $line = (int)$line;
-    if ($line > $previousReading) {
-        $increased++;
-    }
-    $previousReading = $line;
-}
-fclose($inputStream);
-echo $increased; //1553

01/part1.php

@@ -0,0 +1,17 @@
+<?php
+/**
+ *
+ */
+
+$increased = 0;
+$input = file('input', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
+$input = array_map('intval', $input);
+$previousReading = array_shift($input);
+
+foreach ($input as $line) {
+    if ($line > $previousReading) {
+        $increased++;
+    }
+    $previousReading = $line;
+}
+echo $increased; //1553

01/part2.php

@@ -0,0 +1,18 @@
+<?php
+/**
+ *
+ */
+
+$input = file('input', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
+$input = array_map('intval', $input);
+
+$increased       = 0;
+$previousReading = array_sum(array_slice($input, 0, 3));
+for ($i = 1; $i < count($input) - 2; $i++) {
+    $currentReading = array_sum(array_slice($input, $i, 3));
+    if ($currentReading > $previousReading) {
+        $increased++;
+    }
+    $previousReading = $currentReading;
+}
+echo $increased; // 1597

02/part1.php

@@ -0,0 +1,15 @@
+<?php
+
+$increased   = 0;
+$inputStream = fopen('input', 'r');
+$horizontal  = $depth = 0;
+
+while (($line = fgets($inputStream)) !== false) {
+    [$instruction, $value] = explode(' ', trim($line));
+    match ($instruction) {
+        'down' => $depth += (int)$value,
+        'up' => $depth -= (int)$value,
+        'forward' => $horizontal += (int)$value,
+    };
+}
+echo $depth * $horizontal; // 1635930

02/part2.php

@@ -0,0 +1,23 @@
+<?php
+
+$increased   = 0;
+$inputStream = fopen('input', 'r');
+$horizontal  = $depth = $aim = 0;
+
+while (($line = fgets($inputStream)) !== false) {
+    [$instruction, $value] = explode(' ', trim($line));
+    $value = (int)$value;
+    switch ($instruction) {
+        case 'down':
+            $aim   += $value;
+            break;
+        case 'up':
+            $aim   -= $value;
+            break;
+        case 'forward':
+            $horizontal += $value;
+            $depth      += $value * $aim;
+            break;
+    }
+}
+echo $depth * $horizontal; // 1781819478

03/part1.php

@@ -0,0 +1,19 @@
+<?php
+
+$input = file('input', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
+$input = array_map(fn($line) => str_split($line), $input);
+
+$o2 = $co2 = $input;
+
+for ($i = 0; $i < count($input[0]); $i++) {
+    if (count($o2) > 1) {
+        $bit = (int)(array_sum($column = array_column($o2, $i)) >= ceil(count($column) / 2));
+        $o2 = array_filter($o2, fn($line) => $line[$i] == $bit);
+    }
+
+    if (count($co2) > 1) {
+        $bit = (int) (array_sum($column = array_column($co2, $i)) >= ceil(count($column) / 2));
+        $co2 = array_filter($co2, fn ($line) => $line[$i] != $bit);
+    }
+}
+echo bindec(implode('', reset($co2))) * bindec(implode('', reset($o2)));

03/part2.php

@@ -0,0 +1,11 @@
+<?php
+
+$input = file('input', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
+$input = array_map(fn($line) => str_split($line), $input);
+$gamma = $epsilon = [];
+for ($i = 0; $i < count($input[0]); $i++) {
+    $bit = (int) (array_sum($column = array_column($input, $i)) >= ceil(count($column) / 2));
+    $gamma[] = $bit;
+    $epsilon[] = ~$bit & 1;
+}
+echo bindec(implode('', $gamma)) * bindec(implode('', $epsilon)).PHP_EOL;