Added some missing old files and new day2 of 2024.

2024/2/Makefile

@@ -0,0 +1,2 @@
+a.out: main_pt2.cpp
+	clang++ -std=c++2b -g -O0 main_pt2.cpp

2024/2/data_test.txt

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+7 6 4 2 1
+1 2 7 8 9
+9 7 6 2 1
+1 3 2 4 5
+8 6 4 4 1
+1 3 6 7 9

2024/2/main.cpp

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+#include <fstream>
+#include <iostream>
+#include <set>
+#include <sstream>
+#include <string>
+#include <vector>
+
+int main()
+{
+	std::ifstream ifs("data.txt");
+	if(!ifs.is_open())
+	{
+		std::cerr << "Missing data.txt." << std::endl;
+		return -1;
+	}
+
+	unsigned long total = 0;
+	unsigned long total_pt2 = 0;
+
+	for(std::string line; std::getline(ifs, line); )
+	{
+		if(line == "")
+			continue;
+
+		std::istringstream input(line);
+		long *last = nullptr;
+		bool *increasing = nullptr;
+		bool safe = true;
+		for(std::string value; std::getline(input, value, ' '); )
+		{
+			long current;
+			// Get the value:
+			try {
+				current = std::atoi(value.c_str());
+			} catch (const std::exception &e) {
+				break;
+			}
+
+			// See if it's the first value:
+			if(!last)
+			{
+				last = new long(current);
+				continue;
+			}
+
+			// See if it's the second value:
+			if(!increasing)
+			{
+				increasing = new bool(current > *last);
+			}
+
+			auto diff = current - *last;
+			if(*increasing &&
+			   (diff < 1 || diff > 3))
+			{
+				safe = false;
+				break;
+			}
+			if(!*increasing &&
+			   (diff < -3 || diff > -1))
+			{
+				safe = false;
+				break;
+			}
+
+			if(last)
+				*last = current;
+		}
+		if(increasing && last // actually made it through at least 2 values
+		   && safe)
+			total++;
+
+		if(increasing)
+			delete increasing, increasing = nullptr;
+		if(last)
+			delete last, last = nullptr;
+	}
+
+	std::cout << "    Total: " <<     total << std::endl;
+	std::cout << "PT2 Total: " << total_pt2 << std::endl;
+
+	return 0;
+}

2024/2/main_pt2.cpp

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+#include <fstream>
+#include <iostream>
+#include <set>
+#include <sstream>
+#include <string>
+#include <vector>
+
+int main()
+{
+	std::ifstream ifs("data.txt");
+	if(!ifs.is_open())
+	{
+		std::cerr << "Missing data.txt." << std::endl;
+		return -1;
+	}
+
+	unsigned long total = 0;
+	unsigned long total_pt2 = 0;
+
+	std::vector<std::vector<long>> data;
+
+	for(std::string line; std::getline(ifs, line); )
+	{
+		if(line == "")
+			continue;
+
+		// add a row for this line:
+		data.push_back({});
+
+		std::istringstream input(line);
+		// for each value in the line:
+		for(std::string value; std::getline(input, value, ' '); )
+		{
+			try {
+				// add it to the row
+				data.back().push_back(std::atoi(value.c_str()));
+			} catch (const std::exception &e) {
+				break;
+			}
+		}
+	}
+
+	// DEBUG:
+	for(auto row : data)
+	{
+		for(auto col : row)
+			std::cout << col << ", ";
+		std::cout << std::endl;
+	}
+
+	std::cout << "    Total: " <<     total << std::endl;
+	std::cout << "PT2 Total: " << total_pt2 << std::endl;
+
+	return 0;
+}