Add solution for "Day 22: Monkey Market", part 2

src/MonkeyMarket.cpp

@@ -15,6 +15,11 @@
 
 #include <aoc/MonkeyMarket.hpp>
 
+MonkeyMarket::MonkeyMarket(const int inputFileNameSuffix)
+    : Solver{ inputFileNameSuffix }, nBuyers_{ 0 }, sequenceResults_{}
+{
+}
+
 const std::string MonkeyMarket::getPuzzleName() const
 {
     return "Monkey Market";
@@ -28,13 +33,35 @@ const int MonkeyMarket::getPuzzleDay() const
 void MonkeyMarket::processDataLine(const std::string& line)
 {
     uint64_t n{ std::stoull(line) };
+    uint64_t price{ n % getPriceModulo() };
+    uint64_t change;
+    uint64_t newPrice;
+    uint64_t rollingChangeSequence{ 0 };
     for (int i = 0; i < getNSecretNumbers(); i++)
     {
         n = ((n << 6) ^ n) & getPruneValue();
         n = (n >> 5) ^ n;
         n = ((n << 11) ^ n) & getPruneValue();
+        newPrice = n % getPriceModulo();
+        change = getPriceModulo() + newPrice - price;
+        price = newPrice;
+        updateNewRollingChangeSequence(rollingChangeSequence, change);
+        if (i >= 3)
+        {
+            const auto& [it, success] = sequenceResults_.insert({ rollingChangeSequence, { newPrice, nBuyers_ } });
+            if (!success && it->second.second < nBuyers_)
+            {
+                it->second.first += newPrice;
+                it->second.second = nBuyers_;
+                if (it->second.first > part2)
+                {
+                    part2 = it->second.first;
+                }
+            }
+        }
     }
     part1 += n;
+    nBuyers_++;
 }
 
 void MonkeyMarket::finish()
@@ -50,3 +77,15 @@ constexpr uint64_t MonkeyMarket::getPruneValue()
 {
     return 16777215;
 }
+
+constexpr int MonkeyMarket::getPriceModulo()
+{
+    return 10;
+}
+
+void MonkeyMarket::updateNewRollingChangeSequence(uint64_t& rollingChangeSequence, const uint64_t change)
+{
+    // Prices vary from -9 to 9, so we can store the price change plus the price modulo of 10, which is a number between
+    // 1 and 19, as a 5-bit part in this rolling change sequence number and use it as the key in the sequence map.
+    rollingChangeSequence = ((rollingChangeSequence << 5) & 0b11111111111111111111) | change;
+}