Added day 4, part 1 and 2.

2022/4/Makefile

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

2022/4/main.cpp

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+#include <fstream>
+#include <iostream>
+#include <set>
+#include <string>
+#include <vector>
+
+std::vector<std::string> SplitStr(std::string str, const std::string &delim)
+{
+	std::vector<std::string> rtn;
+
+	for(auto split = str.find(delim); split != std::string::npos; split = str.find(delim))
+	{
+		rtn.push_back(str.substr(0, split));
+		str = str.substr(split + delim.size()); // chop off beginning
+	}
+	if(str.size())
+		rtn.push_back(str);
+
+	return rtn;
+}
+
+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;
+
+		auto sections = SplitStr(line, ",");
+		if(sections.size() != 2)
+		{
+			std::cerr << "Incorrect amount of data for line: " << line << std::endl;
+			exit(-1);
+		}
+
+		auto elf_a = SplitStr(sections[0], "-");
+		auto elf_b = SplitStr(sections[1], "-");
+
+		if(elf_a.size() != 2 || elf_b.size() != 2)
+		{
+			std::cerr << "Incorrect amount of data for line: " << line << std::endl;
+			exit(-2);
+		}
+
+		int elf_a_min = std::atoi(elf_a[0].c_str());
+		int elf_a_max = std::atoi(elf_a[1].c_str());
+		int elf_b_min = std::atoi(elf_b[0].c_str());
+		int elf_b_max = std::atoi(elf_b[1].c_str());
+
+		if((elf_a_min <= elf_b_min && elf_a_max >= elf_b_max) ||
+		   (elf_b_min <= elf_a_min && elf_b_max >= elf_a_max))
+			++total;
+
+		// sort
+		if(elf_a_min > elf_b_min)
+		{
+			std::swap(elf_a_min, elf_b_min);
+			std::swap(elf_a_max, elf_b_max);
+		}
+
+		if(elf_b_min <= elf_a_max)
+			++total_pt2;
+	}
+
+	std::cout << "    Total: " <<     total << std::endl;
+	std::cout << "PT2 Total: " << total_pt2 << std::endl;
+
+	return 0;
+}