day5b.cpp

#include <string>
#include <vector>
#include <sstream>
#include <fstream>
#include <cassert>
#include <algorithm>

namespace day5b
{
	int main()
	{
		std::string input0;
		//std::ifstream ifile("day5_sample.txt");
		std::ifstream ifile("day5.txt");
		if (ifile.is_open())
		{
			while (!ifile.eof())
			{
				std::string line;
				std::getline(ifile, line);
				input0 += line + '\n';
			}
			assert(input0.back() == '\n');
			input0.pop_back(); // no trailing newline character please
			//__debugbreak();
		}
		else
		{
			assert(0);
		}

		std::vector<std::string> values;
		std::string temp;
		for (char c : input0)
		{
			if (c == '\n')
			{
				values.push_back(temp);
				temp = "";
				continue;
			}
			temp += c;
		}
		values.push_back(temp);

		std::vector<std::pair<uint64_t, uint64_t>> data1;
		std::vector<uint64_t> data2;

		bool phase_two = false;
		for (int i = 0; i < values.size(); i++)
		{
			if (values[i] == "")
				phase_two = true;
			if (!phase_two)
			{
				std::istringstream ss{ values[i] };
				uint64_t v1;
				char c1;
				uint64_t v2;
				ss >> v1;
				ss >> c1;
				ss >> v2;
				data1.emplace_back(v1, v2);
			}
			else
			{
				std::istringstream ss{ values[i] };
				uint64_t v1;
				ss >> v1;
				data2.emplace_back(v1);
			}
		}

		// sort
		std::sort(begin(data1), end(data1), [](auto& a, auto& b) -> bool { return a.first < b.first; });

		// filter
		for (int i = 0; i < data1.size() - 1; i++)
		{
			auto& curr = data1[i];
			auto& next = data1[i + 1];
			if (next.first <= curr.second)
			{
				curr.second = std::max(curr.second, next.second);
				data1.erase(begin(data1) + i + 1);
				i--;
			}
		}

		// validate
		for (int i = 0; i < data1.size() - 1; i++)
		{
			auto& curr = data1[i];
			auto& next = data1[i + 1];
			assert(curr.first < next.first);
			assert(next.first > curr.second);
		}

		// accumulate
		uint64_t total = 0;
		for (int i = 0; i < data1.size(); i++)
		{
			auto& curr = data1[i];
			total += (curr.second - curr.first + 1);
		}

		__debugbreak();
		return 0;
	}

}