Initial Commit
This commit is contained in:
Jose Caban
279
2022/Day12CSharp/Program.cs
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279
2022/Day12CSharp/Program.cs
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// See https://aka.ms/new-console-template for more information
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using System.Runtime.CompilerServices;
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Part01();
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Part02();
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void Part01()
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{
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Console.WriteLine("!! === Part 1 === !!");
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Console.WriteLine(" === Example ===");
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Tuple<int, int> exampleStart, exampleEnd;
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var exampleHeightMap = HeightMap.LoadHeightMap("example-input.txt", out exampleStart, out exampleEnd);
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var exampleGraph = exampleHeightMap.ToGraph();
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exampleGraph.PrintShortestPath(exampleStart, exampleEnd);
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Console.WriteLine();
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Console.WriteLine(" === Puzzle ===");
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Tuple<int, int> puzzleStart, puzzleEnd;
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var puzzleHeightMap = HeightMap.LoadHeightMap("puzzle-input.txt", out puzzleStart, out puzzleEnd);
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var puzzleGraph = puzzleHeightMap.ToGraph();
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puzzleGraph.PrintShortestPath(puzzleStart, puzzleEnd);
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}
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void Part02()
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{
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Console.WriteLine("!! === Part 2 === !!");
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Console.WriteLine(" === Example ===");
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Tuple<int, int> exampleStart, exampleEnd;
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var exampleHeightMap = HeightMap.LoadHeightMap("example-input.txt", out exampleStart, out exampleEnd);
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var exampleGraph = exampleHeightMap.ToGraph();
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Console.WriteLine("Shortest steps from anywhere: {0}", exampleGraph.GetShortestNumberOfStepsAnywhere(0, exampleEnd));
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Console.WriteLine();
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Console.WriteLine(" === Puzzle ===");
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Tuple<int, int> puzzleStart, puzzleEnd;
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var puzzleHeightMap = HeightMap.LoadHeightMap("puzzle-input.txt", out puzzleStart, out puzzleEnd);
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var puzzleGraph = puzzleHeightMap.ToGraph();
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Console.WriteLine("Shortest steps from anywhere: {0}", puzzleGraph.GetShortestNumberOfStepsAnywhere(0, puzzleEnd));
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}
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class GraphNode
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{
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public int Height { get; set; }
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public Tuple<int, int> Coordinates { get; set; }
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public List<GraphNode> AdjacentNodes { get; set; } = new List<GraphNode>();
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public bool Explored { get; set; }
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public GraphNode(int height, Tuple<int, int> coordinates)
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{
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Height = height;
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Coordinates = coordinates;
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}
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public void Reset()
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{
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Explored = false;
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}
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}
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class Graph
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{
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public Dictionary<Tuple<int, int>, GraphNode> Vertices { get; set; } = new Dictionary<Tuple<int, int>, GraphNode>();
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public GraphNode GetAt(Tuple<int, int> index)
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{
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return Vertices[index];
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}
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public int GetShortestNumberOfStepsAnywhere(int startingHeight, Tuple<int, int> end)
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{
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int minSteps = int.MaxValue;
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foreach (var g in Vertices)
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{
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if (g.Value.Height == startingHeight)
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{
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minSteps = Math.Min(minSteps, GetShortestNumberOfSteps(g.Value.Coordinates, end));
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}
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}
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return minSteps;
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}
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public GraphNode GetAt(int x, int y)
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{
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return GetAt(new Tuple<int, int>(x, y));
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}
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public int GetShortestNumberOfSteps(Tuple<int, int> start, Tuple<int, int> end)
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{
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Dictionary<Tuple<int, int>, Tuple<GraphNode?, int>> path = new Dictionary<Tuple<int, int>, Tuple<GraphNode?, int>>();
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BFS(start, end, path);
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return path[end].Item2;
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}
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public void PrintShortestPath(Tuple<int, int> start, Tuple<int, int> end)
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{
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Console.WriteLine("Shortest path from ({0},{1}) to ({2},{3}): {4} steps", start.Item1, start.Item2, end.Item1, end.Item2, GetShortestNumberOfSteps(start, end));
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}
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public bool BFS(Tuple<int,int> start, Tuple<int,int> end, Dictionary<Tuple<int, int>, Tuple<GraphNode?, int>> path)
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{
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Queue<GraphNode> queue = new Queue<GraphNode>();
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int visited = 0;
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// label all verts as unexplored
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foreach (var g in Vertices)
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{
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g.Value.Reset();
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path.Add(g.Value.Coordinates, new Tuple<GraphNode?, int>(null, int.MaxValue));
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}
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// Get the root
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GraphNode root = GetAt(start);
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Vertices[root.Coordinates].Explored = true;
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path[root.Coordinates] = new Tuple<GraphNode?,int>(path[root.Coordinates].Item1, 0);
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queue.Enqueue(root);
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while (queue.Count != 0)
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{
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GraphNode v = queue.Dequeue();
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// We done if we found it
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if (v.Coordinates.Equals(end))
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{
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return true;
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}
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foreach (var w in v.AdjacentNodes)
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{
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if (!w.Explored)
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{
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visited++;
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//Console.WriteLine("Visited: ({0},{1}). Count: {2}", w.Coordinates.Item1, w.Coordinates.Item2, visited);
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w.Explored = true;
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path[w.Coordinates] = new Tuple<GraphNode?, int>(v, path[v.Coordinates].Item2 + 1);
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queue.Enqueue(w);
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}
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}
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}
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return false;
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}
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}
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class HeightMap
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{
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public Graph ToGraph()
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{
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Graph graph = new Graph();
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// Add in all the verts
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for (int j = 0; j < heightmap.Count; j++)
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{
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for (int i = 0; i < heightmap[0].Count; i++)
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{
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GraphNode gn = new GraphNode(GetHeight(i, j), new Tuple<int, int>(i, j));
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graph.Vertices.Add(gn.Coordinates, gn);
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}
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}
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// Create the edges
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for (int j = 0; j < heightmap.Count; j++)
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{
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for (int i = 0; i < heightmap[0].Count; i++)
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{
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Tuple<int, int> current = new Tuple<int,int>(i, j);
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Tuple<int, int> result = new Tuple<int, int>(0, 0);
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char[] edges = { 'u', 'd', 'l', 'r' };
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foreach (var edge in edges)
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{
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if (CanGo(edge, i, j, out result))
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{
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graph.Vertices[current].AdjacentNodes.Add(graph.Vertices[result]);
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}
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}
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}
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}
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return graph;
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}
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private HeightMap()
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{
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}
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public int GetHeight(int x, int y)
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{
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return heightmap[y][x];
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}
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public bool CanGo(char direction, int x, int y, out Tuple<int,int> newSpot)
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{
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int currentHeight = GetHeight(x, y);
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switch (direction)
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{
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case 'u':
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newSpot = new Tuple<int, int>(x, y - 1);
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return (y > 0 && currentHeight >= GetHeight(x, y - 1) - 1);
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case 'd':
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newSpot = new Tuple<int, int>(x, y + 1);
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return (y < heightmap.Count - 1 && currentHeight >= GetHeight(x, y + 1) - 1);
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case 'l':
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newSpot = new Tuple<int, int>(x - 1, y);
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return (x > 0 && currentHeight >= GetHeight(x - 1, y) - 1);
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case 'r':
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newSpot = new Tuple<int, int>(x + 1, y);
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return (x < heightmap[0].Count - 1 && currentHeight >= GetHeight(x + 1, y) - 1);
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default:
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throw new ArgumentException();
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}
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}
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private List<List<int>> heightmap = new List<List<int>>();
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public static HeightMap LoadHeightMap(string filename, out Tuple<int, int> outStartPoint, out Tuple<int, int> outEndPoint)
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{
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HeightMap hm = new HeightMap();
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Tuple<int, int>? startPoint = null;
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Tuple<int, int>? endPoint = null;
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using (StreamReader reader = System.IO.File.OpenText(filename))
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{
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while (!reader.EndOfStream)
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{
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string? line = reader.ReadLine();
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if (line == null) throw new InvalidDataException();
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List<int> row = new List<int>();
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foreach (char c in line)
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{
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if (!char.IsLetter(c)) throw new InvalidDataException();
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if (c == 'S')
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{
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row.Add('a' - 'a');
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startPoint = new Tuple<int, int>(row.Count - 1, hm.heightmap.Count);
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}
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else if (c == 'E')
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{
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row.Add('z' - 'a');
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endPoint = new Tuple<int, int>(row.Count - 1, hm.heightmap.Count);
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}
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else
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{
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row.Add(c - 'a');
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}
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}
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hm.heightmap.Add(row);
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}
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}
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if (startPoint == null || endPoint == null) throw new InvalidDataException();
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outStartPoint = startPoint;
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outEndPoint = endPoint;
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return hm;
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}
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}
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