Day12

src/days/12/Day12.cpp

@@ -1,9 +1,119 @@
 #include "Day12.h"
 
 Result Day12::Task1() {
-	return Day::Task1();
+	Graph g = parseGraph(false);
+
+	Vertex start = *std::find_if(g.V.begin(), g.V.end(), [this](Vertex v){
+		return input[v.second][v.first] == 'S';
+	});
+	Vertex end = *std::find_if(g.V.begin(), g.V.end(), [this](Vertex v){
+		return input[v.second][v.first] == 'E';
+	});
+
+	map<Day12::Vertex, uint64> distances = dijkstra(g, start);
+
+	uint64 result = distances[end];
+
+	return to_string(result);
 }
 
 Result Day12::Task2() {
-	return Day::Task2();
+	Graph g = parseGraph(true);
+
+	Vertex start = *std::find_if(g.V.begin(), g.V.end(), [this](Vertex v){
+		return input[v.second][v.first] == 'E';
+	});
+
+	set<Vertex> endVertices;
+	std::copy_if(g.V.begin(), g.V.end(), std::inserter(endVertices, endVertices.begin()), [this](Vertex v){
+		char c = input[v.second][v.first];
+		return c == 'a' || c == 'S';
+	});
+
+	map<Day12::Vertex, uint64> distances = dijkstra(g, start);
+
+
+	uint64 result = distances[*std::min_element(endVertices.begin(), endVertices.end(), [&distances](Vertex v1, Vertex v2){
+		return distances[v1] < distances[v2];
+	})];
+
+	return to_string(result);
+}
+
+map<Day12::Vertex, uint64> Day12::dijkstra(Graph &graph, Vertex start) {
+	set<Vertex> queue;
+	map<Vertex, uint64> dist;
+	for (Vertex v : graph.V){
+		dist[v] = UINT64_MAX - 1;
+		queue.insert(v);
+	}
+	dist[start] = 0;
+
+	while (!queue.empty()){
+		Vertex u;
+		uint64 uMin = UINT64_MAX;
+		for (const Vertex &v : queue){
+			if (dist[v] < uMin){
+				uMin = dist[v];
+				u = v;
+			}
+		}
+
+		queue.erase(u);
+
+		for (const Vertex &v : graph.V){
+			if (!graph.E.contains({u, v}) || !queue.contains(v))
+				continue;
+
+			size_t newDist = dist[u] + 1;
+			if (newDist < dist[v])
+				dist[v] = newDist;
+		}
+	}
+	return dist;
+}
+
+Day12::Graph Day12::parseGraph(bool reverse) {
+	Graph g;
+
+	size_t dimX = input[0].size();
+	size_t dimY = input.size();
+
+	for (size_t x = 0; x < dimX; x++)
+		for (size_t y = 0; y < dimY; y++)
+			g.V.emplace(x, y);
+
+	auto invertChar = [](char var){
+		return var + int((double(('a' + 'z')) / 2 - var) * 2);
+	};
+
+	auto readChar = [reverse, invertChar](char var){
+		if (var == 'E')
+			var = 'z';
+		if (var == 'S')
+			var = 'a';
+		if (reverse)
+			var = invertChar(var);
+		return var;
+	};
+
+	auto checkEdges = [&g, readChar, this](Vertex v1, Vertex v2){
+		char c1 = readChar(input[v1.second][v1.first]);
+		char c2 = readChar(input[v2.second][v2.first]);
+		if (c2 <= c1 + 1)
+			g.E.insert({v1, v2});
+		if (c1 <= c2 + 1)
+			g.E.insert({v2, v1});
+	};
+
+	for (Vertex v : g.V){
+		size_t x = v.first;
+		size_t y = v.second;
+		if (x < dimX - 1)
+			checkEdges({x, y}, {x + 1, y});
+		if (y < dimY - 1)
+			checkEdges({x, y}, {x, y + 1});
+	}
+
+	return g;
 }

src/days/12/Day12.h

@@ -3,8 +3,21 @@
 #include "../../Day.h"
 
 class Day12 : public Day {
+
+	typedef pair<size_t, size_t> Vertex;
+	typedef pair<Vertex, Vertex> Edge;
+
+	struct Graph {
+		set<Vertex> V;
+		set<Edge> E;
+	};
+
+	map<Day12::Vertex, uint64> dijkstra(Graph&,Vertex);
+
 protected:
 	Result Task1() override;
 
 	Result Task2() override;
+
+	Graph parseGraph(bool);
 };

src/util.h

@@ -8,6 +8,7 @@
 #include <set>
 #include <map>
 #include <list>
+#include <queue>
 
 typedef uint64_t uint64;
 
@@ -15,6 +16,7 @@ using std::stoi, std::to_string;
 using std::cout, std::endl;
 using std::string, std::vector, std::set, std::pair, std::map;
 using std::list;
+using std::priority_queue;
 
 inline vector<size_t> findAll(const string& data, const string& toSearch){
 	vector<size_t> indices;