Added day 2 and 3, but didn't do them in rust like I wanted to.

2022/3/main.cpp

@@ -0,0 +1,81 @@
+#include <fstream>
+#include <iostream>
+#include <set>
+#include <string>
+#include <vector>
+
+int score(char c)
+{
+	if(c >= 'a' && c <= 'z')
+		return (c - 'a') + 1;
+	return (c - 'A') + 1 + 26;
+}
+
+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;
+
+		const size_t half = line.size() / 2;
+		std::string right = line.substr(half);
+		for(int i = 0; i < half; ++i)
+		{
+			if(right.contains(line[i]))
+			{
+				total += score(line[i]);
+				break;
+			}
+		}
+
+		// Part 2:
+		static std::vector<std::string> lines;
+		lines.push_back(line);
+		if(lines.size() == 3)
+		{
+			// get all letters it could be from first line
+			std::set<char> options;
+			for(const char c : lines[0])
+				options.insert(c);
+
+			// remove if not a duplicate
+			std::set<char> to_remove;
+			for(auto i = 1; i < 3; ++i) // remaining two lines
+			{
+				for(const char c : options)
+					if(!lines[i].contains(c))
+						to_remove.insert(c);
+				for(const char c : to_remove)
+					options.erase(c);
+			}
+
+			if(options.size() != 1)
+			{
+				std::cerr << "Error: More than one remaining option: ";
+				for(const char c : options)
+					std::cout << c << ",";
+				exit(-1);
+			}
+
+			total_pt2 += score(*(options.begin()));
+
+			lines.clear(); // reset
+		}
+	}
+
+	std::cout << "    Total: " <<     total << std::endl;
+	std::cout << "PT2 Total: " << total_pt2 << std::endl;
+
+	return 0;
+}