Added solution to Day 5 Part 1.

2024/5/Makefile

@@ -0,0 +1,2 @@
+a.out: main.cpp
+	clang++ -std=c++2b -g -O0 main.cpp

2024/5/data_test.txt

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+47|53
+97|13
+97|61
+97|47
+75|29
+61|13
+75|53
+29|13
+97|29
+53|29
+61|53
+97|53
+61|29
+47|13
+75|47
+97|75
+47|61
+75|61
+47|29
+75|13
+53|13
+
+75,47,61,53,29
+97,61,53,29,13
+75,29,13
+75,97,47,61,53
+61,13,29
+97,13,75,29,47

2024/5/main.cpp

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+#include <algorithm>
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <set>
+#include <sstream>
+#include <string>
+#include <vector>
+
+int main()
+{
+	const std::string filename = "data.txt";
+	std::ifstream ifs(filename);
+	if(!ifs.is_open())
+	{
+		std::cerr << "Missing " << filename << "." << std::endl;
+		return -1;
+	}
+
+	unsigned long total = 0;
+	unsigned long total_pt2 = 0;
+
+	std::map<long, std::set<long>> rules;
+	std::vector<std::vector<long>> production;
+
+	bool reading_page_numbers = true;
+	for(std::string line; std::getline(ifs, line); )
+	{
+		if(line == "")
+		{
+			// one blank line is the break between reading page numbers and records.
+			if(reading_page_numbers)
+				reading_page_numbers = false;
+
+			continue;
+		}
+
+		std::istringstream input(line);
+		if(reading_page_numbers)
+		{
+			// for each value in the line:
+			std::vector<long> numbers;
+			for(std::string value; std::getline(input, value, '|'); )
+			{
+				try {
+					numbers.push_back(std::atoi(value.c_str()));
+				} catch (const std::exception &e) {
+					std::cout << "Error parsing rule number from " << value << std::endl;
+					exit(-1);
+				}
+			}
+			if(numbers.size() != 2)
+			{
+				std::cout << "Error: Incorrect amount of page numbers (" << numbers.size()
+				          << ") in rules import sequence." << std::endl;
+				exit(-1);
+			}
+			rules[numbers[0]].insert(numbers[1]);
+		}
+		else
+		{
+			// for each value in the line:
+			production.push_back({});
+			for(std::string value; std::getline(input, value, ','); )
+			{
+				try {
+					production.back().push_back(std::atoi(value.c_str()));
+				} catch (const std::exception &e) {
+					std::cout << "Error parsing production number from " << value << std::endl;
+					exit(-1);
+				}
+			}
+		}
+	}
+
+	// // Debug:
+	// std::cout << "RULES:" << std::endl;
+	// for(auto rule : rules)
+	// {
+	// 	std::cout << rule.first << " prints before ";
+	// 	for(auto page : rule.second)
+	// 		std::cout << page << ",";
+	// 	std::cout << std::endl;
+	// }
+	// std::cout << std::endl;
+	// std::cout << "PRODUCTION:" << std::endl;
+	// for(auto row : production)
+	// {
+	// 	for(auto num : row)
+	// 		std::cout << num << ",";
+	// 	std::cout << std::endl;
+	// }
+
+	// For each production run:
+	for(auto row : production)
+	{
+		std::set<long> already_passed;
+		bool bad = false;
+		// For each page number in that production run:
+		for(auto num : row)
+		{
+			// Check against all page numbers it shouldn't print after
+			for(auto before : rules[num])
+			{
+				// If found, it's a bad row!
+				if(std::find(already_passed.begin(), already_passed.end(), before) != already_passed.end())
+				{
+					bad = true;
+					break;
+				}
+			}
+
+			// Keep track of numbers we've looked at already:
+			already_passed.insert(num);
+		}
+
+		if(!bad)
+			total += row[row.size() / 2];
+		// else
+		// 	std::cout << "not ";
+		// std::cout << "safe: ";
+		// for(auto num : row)
+		// 	std::cout << num << ",";
+		// std::cout << std::endl;
+	}
+
+	std::cout << "    Total: " <<     total << std::endl;
+	std::cout << "PT2 Total: " << total_pt2 << std::endl;
+
+	return 0;
+}