.gitignore

@@ -1,2 +1 @@
-/cmake-build-debug/
+/cmake-build-debug/
-/challenge-text/

days/day01.cpp

@@ -12,6 +12,104 @@
 #include <bits/fs_fwd.h>
 #include <bits/fs_path.h>
 
+/*
+--- Day 1: Historian Hysteria ---
+
+The Chief Historian is always present for the big Christmas sleigh launch, but nobody has seen him in months! Last
+anyone heard, he was visiting locations that are historically significant to the North Pole; a group of Senior
+Historians has asked you to accompany them as they check the places they think he was most likely to visit.
+
+As each location is checked, they will mark it on their list with a star. They figure the Chief Historian must be in
+one of the first fifty places they'll look, so in order to save Christmas, you need to help them get fifty stars on
+their list before Santa takes off on December 25th.
+
+Collect stars by solving puzzles. Two puzzles will be made available on each day in the Advent calendar; the second
+puzzle is unlocked when you complete the first. Each puzzle grants one star. Good luck!
+
+You haven't even left yet and the group of Elvish Senior Historians has already hit a problem: their list of locations
+to check is currently empty. Eventually, someone decides that the best place to check first would be the Chief
+Historian's office.
+
+Upon pouring into the office, everyone confirms that the Chief Historian is indeed nowhere to be found. Instead,
+the Elves discover an assortment of notes and lists of historically significant locations! This seems to be the
+planning the Chief Historian was doing before he left. Perhaps these notes can be used to determine which locations
+to search?
+
+Throughout the Chief's office, the historically significant locations are listed not by name but by a unique number
+called the location ID. To make sure they don't miss anything, The Historians split into two groups, each searching
+the office and trying to create their own complete list of location IDs.
+
+There's just one problem: by holding the two lists up side by side (your puzzle input), it quickly becomes clear
+that the lists aren't very similar. Maybe you can help The Historians reconcile their lists?
+
+For example:
+
+3   4
+4   3
+2   5
+1   3
+3   9
+3   3
+
+Maybe the lists are only off by a small amount! To find out, pair up the numbers and measure how far apart they are.
+Pair up the smallest number in the left list with the smallest number in the right list, then the second-smallest left
+number with the second-smallest right number, and so on.
+
+Within each pair, figure out how far apart the two numbers are; you'll need to add up all of those distances.
+For example, if you pair up a 3 from the left list with a 7 from the right list, the distance apart is 4; if you pair
+up a 9 with a 3, the distance apart is 6.
+
+In the example list above, the pairs and distances would be as follows:
+
+    The smallest number in the left list is 1, and the smallest number in the right list is 3. The distance between them is 2.
+    The second-smallest number in the left list is 2, and the second-smallest number in the right list is another 3. The distance between them is 1.
+    The third-smallest number in both lists is 3, so the distance between them is 0.
+    The next numbers to pair up are 3 and 4, a distance of 1.
+    The fifth-smallest numbers in each list are 3 and 5, a distance of 2.
+    Finally, the largest number in the left list is 4, while the largest number in the right list is 9; these are a distance 5 apart.
+
+To find the total distance between the left list and the right list, add up the distances between all the pairs
+you found. In the example above, this is 2 + 1 + 0 + 1 + 2 + 5, a total distance of 11!
+
+Your actual left and right lists contain many location IDs. What is the total distance between your lists?
+
+--- Part Two ---
+
+Your analysis only confirmed what everyone feared: the two lists of location IDs are indeed very different.
+
+Or are they?
+
+The Historians can't agree on which group made the mistakes or how to read most of the Chief's handwriting,
+but in the commotion you notice an interesting detail: a lot of location IDs appear in both lists! Maybe the other
+numbers aren't location IDs at all but rather misinterpreted handwriting.
+
+This time, you'll need to figure out exactly how often each number from the left list appears in the right
+list. Calculate a total similarity score by adding up each number in the left list after multiplying it by the number
+of times that number appears in the right list.
+
+Here are the same example lists again:
+
+3   4
+4   3
+2   5
+1   3
+3   9
+3   3
+
+For these example lists, here is the process of finding the similarity score:
+
+	The first number in the left list is 3. It appears in the right list three times, so the similarity score increases by 3 * 3 = 9.
+	The second number in the left list is 4. It appears in the right list once, so the similarity score increases by 4 * 1 = 4.
+	The third number in the left list is 2. It does not appear in the right list, so the similarity score does not increase (2 * 0 = 0).
+	The fourth number, 1, also does not appear in the right list.
+	The fifth number, 3, appears in the right list three times; the similarity score increases by 9.
+	The last number, 3, appears in the right list three times; the similarity score again increases by 9.
+
+So, for these example lists, the similarity score at the end of this process is 31 (9 + 4 + 0 + 0 + 9 + 9).
+
+Once again consider your left and right lists. What is their similarity score?
+
+ */
 
 void day01::Calculate()
 {
@@ -26,7 +124,7 @@ void day01::Calculate()
 	col2.reserve(estimated_size);
 	occurrence_map.reserve(estimated_size);
 
-	std::ifstream input("input/challenges.txt");
+	std::ifstream input("input/day01.txt");
 
 	if (!input)
 	{

days/day02.cpp

@@ -4,99 +4,54 @@
 
 #include "day02.h"
 
-#include <fstream>
+/*
-#include <iostream>
+--- Day 2: Red-Nosed Reports ---
-#include <iterator>
+
-#include <vector>
+Fortunately, the first location The Historians want to search isn't a long walk from the Chief Historian's office.
-#include <bits/fs_fwd.h>
+
-#include <bits/fs_path.h>
+While the Red-Nosed Reindeer nuclear fusion/fission plant appears to contain no sign of the Chief Historian, the
+engineers there run up to you as soon as they see you. Apparently, they still talk about the time Rudolph was saved
+through molecular synthesis from a single electron.
+
+They're quick to add that - since you're already here - they'd really appreciate your help analyzing some unusual data
+from the Red-Nosed reactor. You turn to check if The Historians are waiting for you, but they seem to have already
+divided into groups that are currently searching every corner of the facility. You offer to help with the unusual data.
+
+The unusual data (your puzzle input) consists of many reports, one report per line. Each report is a list of numbers
+called levels that are separated by spaces. For example:
+
+7 6 4 2 1
+1 2 7 8 9
+9 7 6 2 1
+1 3 2 4 5
+8 6 4 4 1
+1 3 6 7 9
+
+This example data contains six reports each containing five levels.
+
+The engineers are trying to figure out which reports are safe. The Red-Nosed reactor safety systems can only
+tolerate levels that are either gradually increasing or gradually decreasing. So, a report only counts as safe if
+both of the following are true:
+
+    The levels are either all increasing or all decreasing.
+    Any two adjacent levels differ by at least one and at most three.
+
+In the example above, the reports can be found safe or unsafe by checking those rules:
+
+    7 6 4 2 1: Safe because the levels are all decreasing by 1 or 2.
+    1 2 7 8 9: Unsafe because 2 7 is an increase of 5.
+    9 7 6 2 1: Unsafe because 6 2 is a decrease of 4.
+    1 3 2 4 5: Unsafe because 1 3 is increasing but 3 2 is decreasing.
+    8 6 4 4 1: Unsafe because 4 4 is neither an increase or a decrease.
+    1 3 6 7 9: Safe because the levels are all increasing by 1, 2, or 3.
+
+So, in this example, 2 reports are safe.
+
+Analyze the unusual data from the engineers. How many reports are safe?
+
+ */
 
 void day02::Calculate()
 {
-	//std::ifstream input("input/day02short.txt");
-	std::ifstream input("input/day02.txt");
 
-	if (!input)
+}
-	{
-		std::cerr << "Failed to open input file." << std::endl;
-		std::cout << "Current path is " << std::filesystem::current_path() << '\n';
-
-		return;
-	}
-
-	int safeReports = 0;
-	for (std::string line; std::getline(input, line, '\n');)
-	{
-		std::istringstream iss(line);
-		std::vector numbers(std::istream_iterator<int>{iss}, std::istream_iterator<int>());
-		if (IsSafe(numbers, false))
-		{
-			safeReports++;
-		}
-	}
-	std::cout << safeReports << '\n';
-}
-
-bool day02::IsSafe(const std::vector<int> &numbers, const bool secondPass)
-{
-	int previousNumber = numbers.at(numbers.size() - 1);
-	bool increasing = false;
-	bool decreasing = false;
-	bool safe = true;
-	for (int i = numbers.size() - 2; i >= 0; i--)
-	{
-		const int currentNumber = numbers.at(i);
-
-		if (i == numbers.size() - 2)
-		{
-			if (previousNumber < currentNumber)
-			{
-				increasing = true;
-			}
-			if (previousNumber > currentNumber)
-			{
-				decreasing = true;
-			}
-		}
-
-		if (SafetyChecks(currentNumber, previousNumber, increasing, decreasing) == 1 && !secondPass)
-		{
-
-			if (IsSafe(numbers, true))
-			{
-				safe = false;
-				return false;
-			}
-		}
-
-		previousNumber = currentNumber;
-	}
-	if (safe)
-	{
-		return true;
-	}
-	return false;
-}
-
-int day02::SafetyChecks(const int current, const int previous, const bool increasing, const bool decreasing)
-{
-	const int diff = abs(current - previous);
-	if (previous > current && increasing)
-	{
-		return 1;
-	}
-	if (previous < current && decreasing)
-	{
-		return 1;
-	}
-	if (current == previous)
-	{
-		return 1;
-	}
-	if (diff < 1 || diff > 3)
-	{
-		return 1;
-	}
-	//safe
-	return 0;
-}

days/day02.h

@@ -4,17 +4,12 @@
 
 #ifndef DAY02_H
 #define DAY02_H
-#include <vector>
 
 
 class day02
 {
 public:
 	static void Calculate();
-
-	static bool IsSafe(const std::vector<int>& numbers,bool secondPass);
-
-	static int SafetyChecks(int current, int previous, bool increasing, bool decreasing);
 };
 
 #endif //DAY02_H

input/day02short.txt

@@ -1,8 +0,0 @@
-1 3 2 4 5
-8 6 4 4 1
-7 6 4 2 1
-1 2 7 8 9
-9 7 6 2 1
-1 3 6 7 9
-55 55 57 58 59 62 65 68
-22 25 27 28 30 31 32 29