2024 Day 02 part 2

Author: sprak3000

2024/day-02.php

@@ -85,5 +85,5 @@
  * How many reports are now safe?
  */
 
-//$count = $reactorReportParser->findSafeReportsCount($reports, true);
-//print('There are ' . $count . " safe reports after applying the Problem Dampener.\n");
+$count = $reactorReportParser->findSafeReportsCount($reports, true);
+print('There are ' . $count . " safe reports after applying the Problem Dampener.\n");

2024/src/ReactorReportParser.php

@@ -20,30 +20,50 @@ public function findSafeReportsCount(array $reports, bool $applyProblemDampener
         foreach ($reports as $report) {
             $levels = explode(' ', $report);
 
-            $previousChange = '';
-            $isSafeChange = true;
-            $dampenerUsed = false;
+            if ($this->isSafeReport($levels, $applyProblemDampener)) {
+                $this->safeReportsCount++;
+            }
+        }
 
-            for ($i = 1; $i < count($levels); $i++) {
-                $previousLevel = $levels[$i - 1];
-                $currentLevel = $levels[$i];
-                $currentChange = $previousLevel < $currentLevel ? 'increase' : 'decrease';
+        return $this->safeReportsCount;
+    }
 
-                $isSafeChange = $this->isSafeChange($previousLevel, $currentLevel, $previousChange, $currentChange);
+    /**
+     * @param array $levels
+     * @param bool $applyProblemDampener
+     * @return bool
+     */
+    private function isSafeReport(array $levels, bool $applyProblemDampener = false): bool
+    {
+        $previousChange = '';
 
-                if (!$isSafeChange) {
-                    break;
-                }
+        for ($i = 1; $i < count($levels); $i++) {
+            $previousLevel = $levels[$i - 1];
+            $currentLevel = $levels[$i];
+            $currentChange = $previousLevel < $currentLevel ? 'increase' : 'decrease';
+
+            $isSafeChange = $this->isSafeChange($previousLevel, $currentLevel, $previousChange, $currentChange);
 
-                $previousChange = $currentChange;
+            if (!$isSafeChange && !$applyProblemDampener) {
+                return false;
             }
 
-            if ($isSafeChange) {
-                $this->safeReportsCount++;
+            if (!$isSafeChange && $applyProblemDampener) {
+                for ($j = 0; $j < count($levels); $j++) {
+                    $levelsWithoutOneLevel = $levels;
+                    array_splice($levelsWithoutOneLevel, $j, 1, []);
+                    if ($this->isSafeReport($levelsWithoutOneLevel)) {
+                        return true;
+                    }
+                }
+
+                return false;
             }
+
+            $previousChange = $currentChange;
         }
 
-        return $this->safeReportsCount;
+        return true;
     }
 
     /**

2024/tests/ReactorReportParserTest.php

@@ -31,15 +31,12 @@ public function testFindSafeReportsCount()
 
     public function testFindSafeReportsCountUsingProblemDampener()
     {
-        $this->markTestSkipped('TODO...');
-
         // Day 2 Part 2 example inputs
         $result = $this->reactorReportParser->findSafeReportsCount($this->sampleReports, true);
         $this->assertEquals(4, $result);
 
         // Day 2 Part 2 puzzle inputs
-        // 685 is too low
         $result = $this->reactorReportParser->findSafeReportsCount($this->reports, true);
-        $this->assertEquals(660, $result);
+        $this->assertEquals(689, $result);
     }
 }

README.md

@@ -12,7 +12,7 @@ of changes and trends in that community.
 |        | 2024          |     2023      |     2022      |     2021      |     2020      |     2019      |     2018      |     2017      | 2016 |     2015      |
 |-------:|---------------|:-------------:|:-------------:|:-------------:|:-------------:|:-------------:|:-------------:|:-------------:|:----:|:-------------:|
 | Day 01 | :star: :star: | :star: :star: | :star: :star: | :star: :star: | :star: :star: | :star: :star: | :star: :star: | :star: :star: |      | :star: :star: |
-| Day 02 | :star:        | :star: :star: | :star: :star: | :star: :star: | :star: :star: |    :star:     | :star: :star: | :star: :star: |      | :star: :star: |
+| Day 02 | :star: :star: | :star: :star: | :star: :star: | :star: :star: | :star: :star: |    :star:     | :star: :star: | :star: :star: |      | :star: :star: |
 | Day 03 |               |               | :star: :star: | :star: :star: | :star: :star: |               | :star: :star: |               |      | :star: :star: |
 | Day 04 |               |               | :star: :star: |               | :star: :star: |               | :star: :star: | :star: :star: |      | :star: :star: |
 | Day 05 |               |               | :star: :star: |               | :star: :star: |               |               | :star: :star: |      | :star: :star: |