From cf19ba7b610c296874881bd8a6c7be1f921dac07 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stefan=20M=C3=BCller?= <stefan.mueller@aksdb.de>
Date: Fri, 6 Dec 2024 10:20:39 +0100
Subject: [PATCH] Added a page mapping for day 5 to reduce the array size

---
 AdventOfCode2024/PrintQueue.cpp | 24 +++++++++++++++++++-----
 AdventOfCode2024/PrintQueue.h   |  8 ++++++--
 2 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/AdventOfCode2024/PrintQueue.cpp b/AdventOfCode2024/PrintQueue.cpp
index dee3eba..262fca6 100644
--- a/AdventOfCode2024/PrintQueue.cpp
+++ b/AdventOfCode2024/PrintQueue.cpp
@@ -20,11 +20,16 @@
 #include "PrintQueue.h"
 
 PrintQueue::PrintQueue()
-    : Solver{}, isProcessingOrderingRules_{ true }, orderingRules_{}
+    : Solver{}, pageNoMapIndex_{ 0 }, isProcessingOrderingRules_{ true }, orderingRules_{}
 {
     for (size_t i = 0; i <= maxPageNo_; i++)
     {
-        for (size_t j = 0; j <= maxPageNo_; j++)
+        pageNoMap_[i] = -1;
+    }
+
+    for (size_t i = 0; i < nPages_; i++)
+    {
+        for (size_t j = 0; j < nPages_; j++)
         {
             orderingRules_[i][j] = false;
         }
@@ -64,12 +69,21 @@ void PrintQueue::finish()
 {
 }
 
+size_t PrintQueue::getMapped(const int pageNo)
+{
+    if (pageNoMap_[pageNo] < 0)
+    {
+        pageNoMap_[pageNo] = pageNoMapIndex_++;
+    }
+    return pageNoMap_[pageNo];
+}
+
 void PrintQueue::processOrderingRule(const std::string& line)
 {
     auto pos{ line.find("|") };
     auto before{ std::stoi(line.substr(0, pos)) };
     auto after{ std::stoi(line.substr(pos + 1)) };
-    orderingRules_[before][after] = true;
+    orderingRules_[getMapped(before)][getMapped(after)] = true;
 }
 
 void PrintQueue::processUpdatePages(const std::string& line)
@@ -85,7 +99,7 @@ void PrintQueue::processUpdatePages(const std::string& line)
         size_t i{ 0 };
         while (isCorrectOrder && i < pages.size())
         {
-            isCorrectOrder = !orderingRules_[page][pages[i]];
+            isCorrectOrder = !orderingRules_[getMapped(page)][getMapped(pages[i])];
             i++;
         }
         pages.push_back(page);
@@ -100,7 +114,7 @@ void PrintQueue::processUpdatePages(const std::string& line)
         // This works because the input defines a complete ordering on the occurring
         // page numbers.
         std::sort(pages.begin(), pages.end(),
-            [&](int const& a, int const& b) { return orderingRules_[a][b]; });
+            [&](int const& a, int const& b) { return orderingRules_[getMapped(a)][getMapped(b)]; });
         part2 += pages[pages.size() / 2];
     }
 }
diff --git a/AdventOfCode2024/PrintQueue.h b/AdventOfCode2024/PrintQueue.h
index 13d2ffa..5b27e11 100644
--- a/AdventOfCode2024/PrintQueue.h
+++ b/AdventOfCode2024/PrintQueue.h
@@ -27,9 +27,13 @@ class PrintQueue :
     void processDataLine(const std::string& line) override;
     void finish() override;
 private:
-    static const size_t maxPageNo_{ 99 };
+    static const int nPages_{ 49 };
+    static const int maxPageNo_{ 99 };
     bool isProcessingOrderingRules_;
-    bool orderingRules_[maxPageNo_ + 1][maxPageNo_ + 1];
+    int pageNoMapIndex_;
+    int pageNoMap_[maxPageNo_ + 1];
+    bool orderingRules_[nPages_][nPages_];
+    size_t getMapped(const int pageNo);
     void processOrderingRule(const std::string& line);
     void processUpdatePages(const std::string& line);
 };