day3a.cpp

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

namespace day3a
{
	int main()
	{
		std::string input0;
		//std::ifstream ifile("day3_sample.txt");
		std::ifstream ifile("day3.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);
		//__debugbreak();

		std::vector<int> joltages;
		int max_joltage = 0;
		for (auto& bank : values)
		{
			int max0 = -1;
			int max0_pos;
			for (int ix = bank.size() - 2; ix >= 0; ix--)
			{
				char c = bank[ix] - '0';
				if (max0 <= c)
				{
					max0 = c;
					max0_pos = ix;
				}
				// from right to left find the maximum value
				// then from right to left, but stopping before the maximum value find the next largest value
				// the first digit can't be the last digit in the row because you need 2 digits
				// and you want to replace the max if max0_pos is larger as well so you have more chances for the second digit
			}
			int max1 = -1;
			for (int ix = bank.size() - 1; ix > max0_pos; ix--)
			{
				char c = bank[ix] - '0';
				if (max1 < c)
				{
					max1 = c;
				}
			}
			int v = max0 * 10 + max1;
			max_joltage += v;
		}
		
		// 17250 wrong

		__debugbreak();
		return 0;
	}

}