Added solution to problem 15

ProjectEulerCS/ProblemSelection.cs

@@ -31,7 +31,7 @@ namespace ProjectEulerCS{
 		//Holds the valid problem numbers
 		private static readonly List<int> _PROBLEM_NUMBERS = new List<int>()
 				{ 0,  1,  2,  3,  4,  5,  6,  7,  8,  9,
-				 10, 11, 12, 13, 14};
+				 10, 11, 12, 13, 14, 15};
 		public static System.Collections.Generic.List<int> PROBLEM_NUMBERS{
 			get { return _PROBLEM_NUMBERS; }
 		}
@@ -54,6 +54,7 @@ namespace ProjectEulerCS{
 				case 12: problem = new Problem12(); break;
 				case 13: problem = new Problem13(); break;
 				case 14: problem = new Problem14(); break;
+				case 15: problem = new Problem15(); break;
 			}
 			return problem;
 		}

ProjectEulerCS/Problems/Problem15.cs

@@ -0,0 +1,101 @@
+//ProjectEuler/ProjectEulerCS/src/Problems/Problem15.cs
+//Matthew Ellison
+// Created: 08-25-20
+//Modified: 08-25-20
+//How many routes from the top left corner to the bottom right corner are there through a 20×20 grid if you can only move right and down?
+//Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/CSClasses
+/*
+	Copyright (C) 2020  Matthew Ellison
+
+	This program is free software: you can redistribute it and/or modify
+	it under the terms of the GNU Lesser General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU Lesser General Public License for more details.
+
+	You should have received a copy of the GNU Lesser General Public License
+	along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+
+namespace ProjectEulerCS.Problems{
+	public class Problem15 : Problem{
+		//Variables
+		//Static variables
+		private const int WIDTH = 20;	//The width of the box to traverse
+		private const int LENGTH = 20;	//The height of the box to traverse
+		//Instance variables
+		private long numOfRoutes;	//The number of routes from 0, 0 to 20, 20
+		public long NumberOfRoutes{
+			get{
+				if(!solved){
+					throw new Unsolved();
+				}
+				return numOfRoutes;
+			}
+		}
+
+		//Functions
+		//Constructor
+		public Problem15() : base("How many routes from the top left corner to the bottom right corner are there through a 20x20 grid if you can only move right and down?"){
+			numOfRoutes = 0;
+		}
+		//Operational functions
+		//Solve the problems
+		public override void Solve(){
+			//If the problem has already been solved do nothing and end the function
+			if(solved){
+				return;
+			}
+
+			//Start the timer
+			_timer.Start();
+
+			//We write this as a recursive function
+			//When in a location it always moves right first, then down
+			Move(0, 0);
+
+			//Stop the timer
+			_timer.Stop();
+
+			//Throw a flag to show the problem is solved
+			solved = true;
+
+			//Save the results
+			_result = "The number of routes is " + numOfRoutes;
+		}
+		//This function acts as a handler for moving the position on the grid and counting the distance
+		//It moves right first, then down
+		private void Move(int currentX, int currentY){
+			//Check if you are at the end and act accordingly
+			if((currentX == WIDTH) && (currentY == LENGTH)){
+				++numOfRoutes;
+				return;
+			}
+
+			//Move right if possible
+			if(currentX < WIDTH){
+				Move(currentX + 1, currentY);
+			}
+
+			//Move down if possible
+			if(currentY < LENGTH){
+				Move(currentX, currentY + 1);
+			}
+		}
+		//Reset the problem so it can be run again
+		public override void Reset(){
+			base.Reset();
+			numOfRoutes = 0;
+		}
+	}
+}
+
+/* Results
+The number of routes is 137846528820
+It took 17.328 minutes to solve this problem.
+*/