Completed day 2

2020/Makefile

@@ -1,6 +1,9 @@
 day1.out: out/types.o day1.cpp day1.input
 	g++ $(flags) day1.cpp out/types.o -o $@
 
+day2.out: out/types.o day2.cpp day2.input
+	g++ $(flags) day2.cpp out/types.o -o $@
+
 out/types.o: types.hpp types.cpp
 	mkdir -p out/
 	g++ $(flags) -c types.cpp -o $@

2020/day1.cpp

@@ -69,7 +69,7 @@ auto find_2020_x3(const std::vector<i32> & list) -> void {
 	}
 }
 
-i32 main(i32 argc, char * argv[]) {
+auto main(i32 argc, char * argv[]) -> i32 {
 	auto list = std::vector<i32>();
 	{
 		auto line = std::string();

2020/day2.cpp

@@ -0,0 +1,95 @@
+/*******************************************************************************
+ *
+ * Copyright (c) 2020 Gnarwhal
+ *
+ * -----------------------------------------------------------------------------
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files(the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ *******************************************************************************/
+
+#include <vector>
+#include <string>
+#include <iostream>
+#include <fstream>
+
+#include "types.hpp"
+
+struct Password {
+	u32 min;
+	u32 max;
+	char c;
+	std::string password;
+};
+
+auto extract_num(usize & index, const std::string & string) -> u32 {
+	auto num = u32(0);
+	--index;
+	while ('0' <= string[++index] && '9' >= string[index]) {
+		num = (num * 10) + (string[index] - '0');
+	}
+	return num;
+}
+
+auto count_valid_sled(const std::vector<Password> & passwords) -> u32 {
+	auto valid = u32(0);
+	for (auto password : passwords) {
+		auto count = u32(0);
+		for (auto c : password.password) {
+			if (c == password.c) {
+				++count;
+			}
+		}
+		valid += (password.min <= count && count <= password.max);
+	}
+	return valid;
+}
+
+auto count_valid_toboggan(const std::vector<Password> & passwords) -> u32 {
+	auto valid = u32(0);
+	for (auto password : passwords) {
+		if ((password.password[password.min - 1] == password.c)
+		  ^ (password.password[password.max - 1] == password.c)) {
+			++valid;
+		}
+	}
+	return valid;
+}
+
+auto main(i32 argc, char * argv[]) -> i32 {
+	auto passwords = std::vector<Password>();
+	{
+		auto line = std::string();
+		auto file = std::ifstream("day2.input");
+		while (getline(file, line)) {
+			auto index = usize(0);
+			auto password = Password{};
+			password.min      = extract_num(  index, line);
+			password.max      = extract_num(++index, line);
+			password.c        = line[++index];
+			password.password = line.substr(index + 3, line.size() - index - 3);
+			passwords.push_back(password);
+		}
+	}
+
+	std::cout << count_valid_sled(passwords)     << std::endl;
+	std::cout << count_valid_toboggan(passwords) << std::endl;
+
+	return 0;
+}