From 9afba9121a875962f366769e1ad4fa19061e33f6 Mon Sep 17 00:00:00 2001
From: Nick Krichevsky <nick@ollien.com>
Date: Tue, 8 Dec 2020 00:18:26 -0500
Subject: [PATCH] Add day 8 part 1 solution

---
 day8/day8.cpp | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 day8/day8.cpp

diff --git a/day8/day8.cpp b/day8/day8.cpp
new file mode 100644
index 0000000..99a660f
--- /dev/null
+++ b/day8/day8.cpp
@@ -0,0 +1,97 @@
+#include <folly/String.h>
+
+#include <algorithm>
+#include <execution>
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <numeric>
+#include <regex>
+#include <set>
+#include <string_view>
+#include <vector>
+
+constexpr auto ACCUMULATOR_INSTRUCTION = "acc";
+constexpr auto JUMP_INSTRUCTION = "jmp";
+constexpr auto NOP_INSTRUCTION = "nop";
+
+class ProgramLine {
+ public:
+	ProgramLine(std::string instruction, int value) : instruction(instruction), value(value) {
+	}
+
+	const std::string &getInstruction() const {
+		return this->instruction;
+	}
+
+	int getValue() const {
+		return this->value;
+	}
+
+ private:
+	std::string instruction;
+	int value;
+};
+
+std::vector<std::string> readInput(const std::string &filename) {
+	std::vector<std::string> input;
+	std::string line;
+	std::ifstream file(filename);
+	while (std::getline(file, line)) {
+		input.push_back(line);
+	}
+
+	return input;
+}
+
+std::vector<ProgramLine> parseProgramLines(const std::vector<std::string> &input) {
+	std::vector<ProgramLine> lines;
+	lines.reserve(input.size());
+	std::transform(input.cbegin(), input.cend(), std::back_inserter(lines), [](const std::string &line) {
+		std::vector<std::string> lineComponents;
+		folly::split(" ", line, lineComponents);
+		if (lineComponents.size() > 2) {
+			throw new std::invalid_argument("Invalid programspec");
+		}
+
+		return ProgramLine(lineComponents[0], std::stoi(lineComponents[1]));
+	});
+
+	return lines;
+}
+
+int part1(const std::vector<ProgramLine> &lines) {
+	std::set<int> visitedLines;
+	int accumulator = 0;
+	int programCounter = 0;
+	while (true) {
+		ProgramLine line = lines.at(programCounter);
+		if (visitedLines.find(programCounter) != visitedLines.end()) {
+			return accumulator;
+		}
+		visitedLines.insert(programCounter);
+
+		if (line.getInstruction() == JUMP_INSTRUCTION) {
+			programCounter += line.getValue();
+			continue;
+		} else if (line.getInstruction() == ACCUMULATOR_INSTRUCTION) {
+			accumulator += line.getValue();
+		} else if (line.getInstruction() != NOP_INSTRUCTION) {
+			throw new std::invalid_argument("Invalid instruction");
+		}
+
+		programCounter++;
+	}
+}
+
+int main(int argc, char *argv[]) {
+	if (argc != 2) {
+		std::cerr << argv[0] << " <input_file>" << std::endl;
+		return 1;
+	}
+
+	auto input = readInput(argv[1]);
+	auto programLines = parseProgramLines(input);
+
+	std::cout << part1(programLines) << std::endl;
+}