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README.md

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 # AdventOfCode2024
 
-Solver for Advent of Code 2024 puzzles. https://adventofcode.com/2024/
+Solver for Advent of Code 2024 puzzles. <https://adventofcode.com/2024/>
+
+This is a single command line application for the puzzles written in [C++17](https://en.cppreference.com/w/cpp/17) with [Visual Studio 2022](https://visualstudio.microsoft.com/vs/) (v143).
+
+## Puzzle Input
+
+This project does not contain the puzzle or example inputs as per the [copyright notice of Advent of Code](https://adventofcode.com/about). In order to run the compiled application, the puzzle inputs have to be downloaded from the [Advent of Code 2024](https://adventofcode.com/2024/) puzzle pages, and placed as text files into the `AdventOfCode2024\data` directory, e.g. `AdventOfCode2024\data\historian_hysteria.txt`, or `AdventOfCode2024\data\example\historian_hysteria.txt` for the unit tests. The application will output an error message with details if it cannot find an input file.
+
+## Tests
+
+The solution contains a unit test project to help troubleshoot issues and prevent regressions in the solver class framework. These tests cover the solutions for provided examples and full data inputs. I did not find a definitive source for it, but the full data inputs seem to be user-specific, so adding my solutions as tests does not spoil the solutions.
+
+## Solutions
+
+### Day 1: Historian Hysteria
+
+:mag_right: Puzzle: <https://adventofcode.com/2024/day/1>, :white_check_mark: Solver: [`HistorianHysteria.cpp`](AdventOfCode2024/HistorianHysteria.cpp)
+
+I'm using a `std::multiset` to collect and sort the values for both lists. This allows to use a single iteration of the left list and two iterations of the right list simultaneously to solve both parts. Nice application of iterators.
 
 ## License