Day 4

src/days/04/Day04.cpp

@@ -1,9 +1,62 @@
 #include "Day04.h"
+#include <cmath>
 
 Result Day04::Task1() {
-    return Day::Task1();
+	uint64 sum = 0;
+
+	for (const auto &[winning, having] : parseCards()){
+		std::set<uint8_t> result;
+		std::set_intersection(winning.begin(), winning.end(), having.begin(), having.end(), std::inserter(result, result.begin()));
+		if (!result.empty()){
+			sum += uint64(powl(2, result.size() - 1));
+		}
+	}
+
+    return to_string(sum);
 }
 
 Result Day04::Task2() {
-    return Day::Task2();
+	vector<uint64> matches;
+
+	for (const auto &[winning, having] : parseCards()){
+		std::set<uint8_t> result;
+		std::set_intersection(winning.begin(), winning.end(), having.begin(), having.end(), std::inserter(result, result.begin()));
+		matches.push_back(result.size());
+	}
+
+	vector<uint64> counts(matches.size(), 1);
+
+	for (size_t i = 0; i < matches.size(); i++){
+		for (size_t instance = 0; instance < counts[i]; instance++){
+			for (size_t k = 0; k < matches[i]; k++){
+				counts[i + k + 1]++;
+			}
+		}
+	}
+
+	uint64 sum = std::reduce(counts.begin(), counts.end(), 0, [](uint64 a, uint64 b){return a + b;});
+
+	return to_string(sum);
+}
+
+vector<Day04::Card> Day04::parseCards() const {
+	vector<Card> cards;
+
+	for (string line : input){
+		line = line.substr(line.find(':') + 1);
+		string left = line.substr(0, line.find(" |"));
+		string right = line.substr(line.find(" |") + 2);
+
+		set<uint8_t> winning;
+		for (size_t i = 0; i < left.length(); i += 3)
+			winning.insert(std::stoul(left.substr(i, 3)));
+
+		set<uint8_t> having;
+		for (size_t i = 0; i < right.length(); i += 3)
+			having.insert(std::stoul(right.substr(i, 3)));
+
+		cards.emplace_back(winning, having);
+	}
+
+	return cards;
 }

src/days/04/Day04.h

@@ -3,8 +3,11 @@
 #include "../../Day.h"
 
 class Day04 : public Day {
+	typedef pair<set<uint8_t>, set<uint8_t>> Card;
 protected:
     Result Task1() override;
 
     Result Task2() override;
+
+	vector<Card> parseCards() const;
 };