Day 2 solution.

2025/inputs/day_2_input.txt

@@ -0,0 +1 @@
+851786270-851907437,27-47,577-1044,1184-1872,28214317-28368250,47766-78575,17432-28112,2341-4099,28969-45843,5800356-5971672,6461919174-6461988558,653055-686893,76-117,2626223278-2626301305,54503501-54572133,990997-1015607,710615-802603,829001-953096,529504-621892,8645-12202,3273269-3402555,446265-471330,232-392,179532-201093,233310-439308,95134183-95359858,3232278502-3232401602,25116215-25199250,5489-8293,96654-135484,2-17

2025/src/Days/Day2.php

@@ -1,17 +1,64 @@
 <?php
-
 namespace Aoc2025\Days;
-
 use Aoc2025\Day;
 
 class Day2 extends Day {
-
+  
+  private function isInvalidId($num) {
+    $str = (string)$num;
+    $len = strlen($str);
+    
+    // Try all possible pattern lengths (from 1 to len/2)
+    for ($patternLen = 1; $patternLen <= $len / 2; $patternLen++) {
+      // Only check if the pattern length divides evenly into total length
+      if ($len % $patternLen !== 0) {
+        continue;
+      }
+      
+      $pattern = substr($str, 0, $patternLen);
+      $repetitions = $len / $patternLen;
+      
+      // Must repeat at least twice
+      if ($repetitions < 2) {
+        continue;
+      }
+      
+      // Check if the entire string is this pattern repeated
+      $repeated = str_repeat($pattern, $repetitions);
+      if ($repeated === $str) {
+        return true;
+      }
+    }
+    
+    return false;
+  }
+  
   public function run() {
     $input = $this->getInputFile('day_2_input.txt');
     
+    // Parse ranges
+    $ranges = explode(',', trim($input));
+    $sumPart1 = 0;
+    $sumPart2 = 0;
+    
+    foreach ($ranges as $range) {
+      $range = trim($range);
+      list($start, $end) = explode('-', $range);
+      $start = (int)$start;
+      $end = (int)$end;
+      
+      // Check each number in range
+      for ($id = $start; $id <= $end; $id++) {
+        if ($this->isInvalidId($id)) {
+          $sumPart2 += $id;
+        }
+      }
+
+    }
+    
     return [
-      'part_1' => 0,
-      'part_2' => 0,
+      'part_1' => $sumPart1, 
+      'part_2' => $sumPart2,
     ];
   }
 }