add csharp examples (#10)

07_dijkstras_algorithm/csharp/01_dijkstras_algorithm/.gitignore

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+**/bin/*
+**/obj/*

07_dijkstras_algorithm/csharp/01_dijkstras_algorithm/.vscode/launch.json

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+{
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": ".NET Core Launch (console)",
+            "type": "coreclr",
+            "request": "launch",
+            "preLaunchTask": "build",
+            "program": "${workspaceRoot}/bin/Debug/netcoreapp1.0/01_dijkstras_algorithm.dll",
+            "args": [],
+            "cwd": "${workspaceRoot}",
+            "externalConsole": false,
+            "stopAtEntry": false,
+            "internalConsoleOptions": "openOnSessionStart"
+        },
+        {
+            "name": ".NET Core Attach",
+            "type": "coreclr",
+            "request": "attach",
+            "processId": "${command.pickProcess}"
+        }
+    ]
+}

07_dijkstras_algorithm/csharp/01_dijkstras_algorithm/.vscode/tasks.json

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+{
+    "version": "0.1.0",
+    "command": "dotnet",
+    "isShellCommand": true,
+    "args": [],
+    "tasks": [
+        {
+            "taskName": "build",
+            "args": [
+                "${workspaceRoot}/project.json"
+            ],
+            "isBuildCommand": true,
+            "problemMatcher": "$msCompile"
+        }
+    ]
+}

07_dijkstras_algorithm/csharp/01_dijkstras_algorithm/Program.cs

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+using System;
+using System.Collections.Generic;
+
+namespace ConsoleApplication
+{
+    public class Program
+    {
+        private const double _infinity = double.PositiveInfinity;
+        private static Dictionary<string, Dictionary<string, double>> _graph = new Dictionary<string, Dictionary<string, double>>();
+        private static List<string> _processed = new List<string>();
+
+        public static void Main(string[] args)
+        {
+            _graph.Add("start", new Dictionary<string, double>());
+            _graph["start"].Add("a", 6.0);
+            _graph["start"].Add("b", 2.0);
+
+            _graph.Add("a", new Dictionary<string, double>());
+            _graph["a"].Add("fin", 1.0);
+
+            _graph.Add("b", new Dictionary<string, double>());
+            _graph["b"].Add("a", 3.0);
+            _graph["b"].Add("fin", 5.0);
+
+            _graph.Add("fin", new Dictionary<string, double>());
+
+            var costs = new Dictionary<string, double>();
+            costs.Add("a", 6.0);
+            costs.Add("b", 2.0);
+            costs.Add("fin", _infinity);
+
+            var parents = new Dictionary<string, string>();
+            parents.Add("a", "start");
+            parents.Add("b", "start");
+            parents.Add("fin", null);
+
+            var node = FindLowestCostNode(costs);
+            while (node != null)
+            {
+                var cost = costs[node];
+                var neighbors = _graph[node];
+                foreach (var n in neighbors.Keys)
+                {
+                    var new_cost = cost + neighbors[n];
+                    if (costs[n] > new_cost)
+                    {
+                        costs[n] = new_cost;
+                        parents[n] = node;
+                    }
+                }
+                _processed.Add(node);
+                node = FindLowestCostNode(costs);
+            }
+            Console.WriteLine(string.Join(", ", costs));
+        }
+
+        private static string FindLowestCostNode(Dictionary<string, double> costs)
+        {
+            var lowestCost = double.PositiveInfinity;
+            string lowestCostNode = null;
+            foreach (var node in costs)
+            {
+                var cost = node.Value;
+                if (cost < lowestCost && !_processed.Contains(node.Key))
+                {
+                    lowestCost = cost;
+                    lowestCostNode = node.Key;
+                }
+            }
+            return lowestCostNode;
+        }
+    }
+}

07_dijkstras_algorithm/csharp/01_dijkstras_algorithm/project.json

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+{
+  "version": "1.0.0-*",
+  "buildOptions": {
+    "debugType": "portable",
+    "emitEntryPoint": true
+  },
+  "dependencies": {},
+  "frameworks": {
+    "netcoreapp1.0": {
+      "dependencies": {
+        "Microsoft.NETCore.App": {
+          "type": "platform",
+          "version": "1.0.1"
+        }
+      },
+      "imports": "dnxcore50"
+    }
+  }
+}