From 14ff577615003c76c44eb5acaea05c2946cd6cbb Mon Sep 17 00:00:00 2001
From: Benjamin Kraft <benjamin.kraft@online.de>
Date: Mon, 18 Dec 2023 13:44:55 +0100
Subject: [PATCH] Day 3

---
 src/days/03/Day03.cpp | 99 +++++++++++++++++++++++++++++++++++++++++--
 src/days/03/Day03.h   |  3 ++
 src/util.h            | 14 ++++++
 3 files changed, 113 insertions(+), 3 deletions(-)

diff --git a/src/days/03/Day03.cpp b/src/days/03/Day03.cpp
index dad3568..fa36133 100644
--- a/src/days/03/Day03.cpp
+++ b/src/days/03/Day03.cpp
@@ -1,9 +1,102 @@
 #include "Day03.h"
 
 Result Day03::Task1() {
-    return Day::Task1();
+	uint32_t sum = 0;
+
+	auto isSymbol = [this](int32_t x, int32_t y) -> bool {
+		if (x < 0 || x > input[0].length() - 1 ||
+			y < 0 || y > input.size() - 1){
+			return false;
+		}
+		char c = input[y][x];
+		return !isDigit(c) && c != '.';
+	};
+
+	for (const auto &[number, position] : parseEngineNumbers()){
+		auto &[value, size] = number;
+		auto &[x, y] = position;
+
+		bool symbolFound = false;
+		for (int32_t sx = x - 1; sx < x + size + 1; sx++){
+			for (int32_t sy = y - 1; sy < y + 2; sy++){
+				if (isSymbol(sx, sy)){
+					symbolFound = true;
+					break;
+				}
+			}
+		}
+		if (symbolFound)
+			sum += value;
+	}
+
+    return to_string(sum);
 }
 
 Result Day03::Task2() {
-    return Day::Task2();
-}
\ No newline at end of file
+	uint32_t sum = 0;
+
+	map<pair<size_t, size_t>, set<EngineNumber>> stars;
+
+	auto isStar = [this](int32_t x, int32_t y) -> bool {
+		if (x < 0 || x > input[0].length() - 1 ||
+			y < 0 || y > input.size() - 1){
+			return false;
+		}
+		return input[y][x] == '*';
+	};
+
+	for (const auto &[number, position] : parseEngineNumbers()){
+		auto &[value, size] = number;
+		auto &[x, y] = position;
+
+		for (int32_t sx = x - 1; sx < x + size + 1; sx++){
+			for (int32_t sy = y - 1; sy < y + 2; sy++){
+				if (isStar(sx, sy)){
+					if (stars.contains({sx, sy})){
+						stars[{sx, sy}].insert({number, position});
+					} else {
+						stars[{sx, sy}] = {{number, position}};
+					}
+				}
+			}
+		}
+	}
+
+	for (auto &[position, numbers] : stars){
+		if (numbers.size() == 2){
+			sum += numbers.begin()->first.first * (++numbers.begin())->first.first;
+		}
+	}
+
+	return to_string(sum);
+}
+
+vector<Day03::EngineNumber> Day03::parseEngineNumbers() const {
+	vector<EngineNumber> numbers;
+
+	for (size_t y = 0; y < input.size(); y++){
+		const string& line = input[y];
+		uint32_t value = 0;
+		uint8_t valueLength = 0;
+		bool readingValue = false;
+
+		for (size_t x = 0; x < line.length(); x++){
+			uint8_t digit;
+			if (isDigit(line[x], digit)){
+				value = value * 10 + digit;
+				valueLength++;
+				readingValue = true;
+				if (x == line.length() - 1)
+					numbers.push_back({{value, valueLength}, {x - valueLength, y}});
+			} else {
+				if (readingValue)
+					numbers.push_back({{value, valueLength}, {x - valueLength, y}});
+				readingValue = false;
+				valueLength = 0;
+				value = 0;
+			}
+		}
+	}
+
+	return numbers;
+}
diff --git a/src/days/03/Day03.h b/src/days/03/Day03.h
index 0ff555a..3d98cdd 100644
--- a/src/days/03/Day03.h
+++ b/src/days/03/Day03.h
@@ -3,8 +3,11 @@
 #include "../../Day.h"
 
 class Day03 : public Day {
+	typedef pair<pair<uint32_t, uint8_t>, pair<int32_t, int32_t>> EngineNumber;
 protected:
     Result Task1() override;
 
     Result Task2() override;
+
+	vector<EngineNumber> parseEngineNumbers() const;
 };
\ No newline at end of file
diff --git a/src/util.h b/src/util.h
index 12596ac..20c1636 100644
--- a/src/util.h
+++ b/src/util.h
@@ -39,4 +39,18 @@ inline void removeAll(string& data, const string& toRemove) {
 	std::sort(indices.rbegin(), indices.rend());
 	for (size_t &i : indices)
 		data.erase(i, toRemove.size());
+}
+
+inline bool isDigit(char c, uint8_t& result){
+	auto val = c - '0';
+	if (val >= 0 && val < 10){
+		result = val;
+		return true;
+	}
+	return false;
+}
+
+inline bool isDigit(char c){
+	auto val = c - '0';
+	return val >= 0 && val < 10;
 }
\ No newline at end of file