✨ Finit le jour 16

day_16/part_1.php

@@ -0,0 +1,58 @@
+<?php
+
+[$instructions, $mine, $others] = explode("\n\n", file_get_contents('input.txt'));
+
+// parse instructions
+function parseInstructions($instructions)
+{
+    // class: 1-3 or 5-7
+    preg_match_all('/^[a-z]+: (\d+)-(\d+) or (\d+)-(\d+)$/mi', $instructions, $matches);
+    if (count($matches) !== 5) {
+        echo sprintf('Regex failed : %s', var_export($matches, true));
+        exit;
+    }
+
+    $compares = [];
+    array_shift($matches);
+    for ($i = 0, $l = count($matches[0]); $i < $l; $i++) {
+        $compares[] = static function ($number) use ($matches, $i) {
+            $comparison = ($number >= (int)$matches[0][$i] and $number <= (int)$matches[1][$i])
+                || ($number >= (int)$matches[2][$i] and $number <= (int)$matches[3][$i]);
+            if ($comparison === true) {
+                return true;
+            }
+            return $number;
+        };
+    }
+
+    return $compares;
+}
+
+$compares = parseInstructions($instructions);
+
+// check others
+$others = explode("\n", $others);
+array_shift($others);
+$others = array_map(static function($other) {
+    return explode(',', $other);
+}, $others);
+
+$sum = 0;
+foreach ($others as $other) {
+    foreach ($other as $number) {
+        $is_valid = false;
+        foreach ($compares as $compare) {
+            if ($compare((int)$number) === true) {
+                $is_valid = true;
+                break;
+            }
+        }
+        if (!$is_valid) {
+            $sum += $number;
+            echo sprintf('%u not in comparison list%s', $number, "\n");
+        }
+    }
+}
+
+// sum it up
+echo $sum;

day_16/part_2.php

@@ -0,0 +1,105 @@
+<?php
+
+[$instructions, $mine, $others] = explode("\n\n", file_get_contents('input.txt'));
+
+// parse instructions
+function parseInstructions($instructions): array
+{
+    // for example : « class: 1-3 or 5-7 »
+    preg_match_all('/^([a-z ]+): (\d+)-(\d+) or (\d+)-(\d+)$/mi', $instructions, $matches);
+    if (count($matches) !== 6) {
+        echo sprintf('Regex failed : %s', var_export($matches, true));
+        exit;
+    }
+
+    $compares = [];
+    array_shift($matches);
+    for ($i = 0, $l = count($matches[0]); $i < $l; $i++) {
+        $compares[$matches[0][$i]] = static function ($number) use ($matches, $i) {
+            $comparison = ($number >= (int)$matches[1][$i] and $number <= (int)$matches[2][$i])
+                || ($number >= (int)$matches[3][$i] and $number <= (int)$matches[4][$i]);
+            if ($comparison === true) {
+                return true;
+            }
+            return $number;
+        };
+    }
+
+    return $compares;
+}
+
+$compares = parseInstructions($instructions);
+
+// check valid others
+$others = explode("\n", $others);
+array_shift($others);
+$others = array_map(static function($other) {
+    return explode(',', $other);
+}, $others);
+
+// filter by valid tickets
+$valid_tickets = [];
+foreach ($others as $other) {
+    $is_valid = 0;
+    foreach ($other as $number) {
+        foreach ($compares as $compare) {
+            if ($compare((int)$number) === true) {
+                $is_valid++;
+                break;
+            }
+        }
+    }
+    if ($is_valid === 20) {
+        $valid_tickets[] = $other;
+    }
+}
+
+// filter columns by what they CAN'T be
+$cant_be = [];
+foreach ($valid_tickets as $valid_ticket) {
+    foreach ($valid_ticket as $row => $number) {
+        foreach ($compares as $name => $compare) {
+            if ($compare((int)$number) !== true) {
+                if (
+                    !array_key_exists($row, $cant_be) ||
+                    (array_key_exists($row, $cant_be) && !in_array($name, $cant_be[$row], true))
+                ) {
+                    $cant_be[$row][] = $name;
+                }
+            }
+        }
+    }
+}
+
+$columns = [];
+$labels = array_keys($compares);
+
+uasort($cant_be, static function($a, $b) {
+    return count($a) >= count($b) ? -1 : 1;
+});
+
+// label columns
+foreach ($cant_be as $row => $labels_cant_be) {
+    foreach ($labels as $i => $label_cant_be) {
+        if (!in_array($label_cant_be, $labels_cant_be, true)) {
+            $columns[$row] = $label_cant_be;
+            unset($labels[$i]);
+            break;
+        }
+    }
+}
+
+ksort($columns);
+
+// compare to mine
+$mine = explode("\n", $mine);
+array_shift($mine);
+$mine = explode(',', current($mine));
+$departure_fields = [];
+foreach ($columns as $row => $column) {
+    if (strpos($column, 'departure') === 0) {
+        $departure_fields[] = $mine[$row];
+    }
+}
+
+echo array_product($departure_fields);