Added solution to problem 15

Problems/Problem15.ts

@@ -0,0 +1,108 @@
+//ProjectEulerTS/Problems/Problem15.ts
+//Matthew Ellison
+// Created: 03-29-21
+//Modified: 03-29-21
+//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/typescriptClasses
+/*
+	Copyright (C) 2021  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/>.
+*/
+
+
+import { Unsolved } from "../Unsolved";
+import { Problem } from "./Problem";
+
+
+export class Problem15 extends Problem{
+	//Variables
+	//Static variables
+	private static WIDTH: number = 20;	//The width of the box to traverse
+	private static LENGTH: number = 20;	//The height of the box to traverse
+	//Instance variables
+	private numOfRoutes: number;	//The number of routes from 0, 0 to 20, 20
+
+	//Functions
+	//Constructor
+	public constructor(){
+		super(`How many routes from the top left corner to the bottom right corner are there through a ${Problem15.WIDTH}x${Problem15.LENGTH} grid if you can only move right and down?`);
+		this.numOfRoutes = 0;
+	}
+	//Operational functions
+	//Solve the problem
+	public solve(): void{
+		//If the problem has already been solved do nothing and end the function
+		if(this.solved){
+			return;
+		}
+
+		//Start the timer
+		this.timer.start();
+
+		//We write this as a recursive function
+		//When in a location it always move right first, then down
+		this.move(0, 0);
+
+		//Stop the timer
+		this.timer.stop();
+
+		//Throw a flag to show the problem is solved
+		this.solved = true;
+	}
+	//This function acts as a handler for moving the position on the grid and counting the disctance
+	//It moves right first, then down
+	private move(currentX: number, currentY: number): void{
+		//Check if you are at the end and act accordingly
+		if((currentX == Problem15.WIDTH) && (currentY == Problem15.LENGTH)){
+			++this.numOfRoutes;
+			return;
+		}
+
+		//Move right if possible
+		if(currentX < Problem15.WIDTH){
+			this.move(currentX + 1, currentY);
+		}
+
+		//Move down if possible
+		if(currentY < Problem15.LENGTH){
+			this.move(currentX, currentY + 1);
+		}
+	}
+	//Reset the problem so it can be run again
+	public reset(): void{
+		super.reset();
+		this.numOfRoutes = 0;
+	}
+	//Gets
+	//Returns the result of solving the problem
+	public getResult(): string{
+		if(!this.solved){
+			throw new Unsolved();
+		}
+		return `The number of routes is ${this.numOfRoutes}`;
+	}
+	//Returns the number of routes found
+	public getNumberOfRoutes(): number{
+		if(!this.solved){
+			throw new Unsolved();
+		}
+		return this.numOfRoutes;
+	}
+}
+
+/* Results:
+The number of routes is 137846528820
+It took 37.058 minutes to solve this problem.
+*/