diff --git a/day_3/part_2.php b/day_3/part_2.php
new file mode 100644
index 0000000..912d386
--- /dev/null
+++ b/day_3/part_2.php
@@ -0,0 +1,36 @@
+<?php
+
+$banks = explode("\n", file_get_contents('./input.txt'));
+
+$output_joltage = [];
+
+foreach ($banks as $bank) {
+    $a_bank = str_split($bank);
+    $a_bank_length = count($a_bank);
+    $max_index = $a_bank_length - 12;
+    $min_index = 0;
+
+    $bank_joltage = [];
+
+    while (count($bank_joltage) < 12) {
+        $slice = array_slice($a_bank, 0, $max_index);
+        $max = max($slice);
+        $min_index = array_search($max, $a_bank);
+        $bank_joltage[] = $max;
+
+        array_splice($a_bank, 0, $min_index+1);
+        if (count($a_bank) + count($bank_joltage) === 12) {
+            $bank_joltage = array_merge($bank_joltage, $a_bank);
+        }
+        $a_bank_length = count($a_bank);
+        $max_index = $a_bank_length - 11 + count($bank_joltage);
+
+    }
+
+    $largest_voltage = (int)implode('', $bank_joltage);
+    $output_joltage[] = $largest_voltage;
+    echo $largest_voltage . "\n";
+
+}
+
+echo array_sum($output_joltage);
\ No newline at end of file
diff --git a/day_4/part_1.php b/day_4/part_1.php
new file mode 100644
index 0000000..811a5df
--- /dev/null
+++ b/day_4/part_1.php
@@ -0,0 +1,54 @@
+<?php
+
+$grid = array_map(fn($line) => str_split($line), array_filter(explode("\n", file_get_contents(__DIR__.'/input.txt')), static fn($line) =>!empty($line)));
+
+$count = 0;
+
+do {
+    $local_count = 0;
+    $removed_papers = [];
+    foreach ($grid as $i => $line) {
+        foreach ($line as $j => $cell) {
+            switch ($cell) {
+                case '@':
+                    if (count_adjacents($i, $j) < 4) {
+                        $local_count++;
+                        $removed_papers[] = [$i, $j];
+                    }
+                    break;
+                case '.':
+                default:
+                    break;
+            }
+        }
+    }
+
+    foreach ($removed_papers as $removed_paper) {
+        $grid[$removed_paper[0]][$removed_paper[1]] = '.';
+    }
+
+    $count += $local_count;
+} while ($local_count !== 0);
+
+echo $count;
+
+function count_adjacents(int $i, int $j): int
+{
+    global $grid;
+    $count = 0;
+    if (array_key_exists($i - 1, $grid)) {
+        if (array_key_exists($j - 1, $grid[$i - 1]) && $grid[$i - 1][$j - 1] === '@') $count++;
+        if ($grid[$i - 1][$j] === '@') $count++;
+        if (array_key_exists($j + 1, $grid[$i - 1]) && $grid[$i - 1][$j + 1] === '@') $count++;
+    }
+
+    if (array_key_exists($j - 1, $grid[$i]) && $grid[$i][$j - 1] === '@') $count++;
+    if (array_key_exists($j + 1, $grid[$i]) && $grid[$i][$j + 1] === '@') $count++;
+
+    if (array_key_exists($i + 1, $grid)) {
+        if (array_key_exists($j - 1, $grid[$i + 1]) && $grid[$i + 1][$j - 1] === '@') $count++;
+        if ($grid[$i + 1][$j] === '@') $count++;
+        if (array_key_exists($j + 1, $grid[$i + 1]) && $grid[$i + 1][$j + 1] === '@') $count++;
+    }
+    return $count;
+}
\ No newline at end of file
diff --git a/day_4/part_2.php b/day_4/part_2.php
new file mode 100644
index 0000000..e69de29