Restructured project and updated day 3

2020/days/day1.cpp

@@ -0,0 +1,86 @@
+/*******************************************************************************
+ *
+ * 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 <algorithm>
+#include <string>
+#include <iostream>
+#include <fstream>
+
+#include "../misc/types.hpp"
+#include "../misc/print.hpp"
+
+// Find 2 numbers that sum to 2020
+auto find_2020_x2(const std::vector<i32> & list) -> void {
+	auto begin = 0;
+	auto end   = list.size() - 1;
+	auto sum   = 0;
+	while ((sum = list[begin] + list[end]) != 2020) {
+		if (sum < 2020) {
+			++begin;
+		} else {
+			--end;
+		}
+	}
+	print((list[begin] * list[end]));
+}
+
+// Find 3 numbers that sum to 2020
+auto find_2020_x3(const std::vector<i32> & list) -> void {
+	for (auto n0 = 0; n0 < list.size() - 2; ++n0) {
+		for (auto n1 = 1; n1 < list.size() - 1; ++n1) {
+			auto low  = n0 + 1;
+			auto high = n1;
+			while (low < high) {
+				auto n2  = (low + high) / 2;
+				auto sum = 0;
+				if ((sum = list[n0] + list[n1] + list[n2]) == 2020) {
+					print((list[n0] * list[n1] * list[n2]));
+					return;
+				} else if (sum < 2020) {
+					low = n2 + 1;
+				} else {
+					high = n2;
+				}
+			}
+		}
+	}
+}
+
+auto day1() -> void {
+	auto list = std::vector<i32>();
+	{
+		auto line = std::string();
+		auto file = std::ifstream("inputs/day1.input");
+		while (getline(file, line)) {
+			list.push_back(std::stoi(line));
+		}
+	}
+	std::sort(list.begin(), list.end());
+
+	find_2020_x2(list);
+	find_2020_x3(list);
+}