Added solution to problem 20

Problems/Problem20.ts

@@ -0,0 +1,118 @@
+//ProjectEulerTS/Problems/Problem19.ts
+//Matthew Ellison
+// Created: 04-07-21
+//Modified: 04-07-21
+//What is the sum of the digits of 100!?
+//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 Problem20 extends Problem{
+	//Variables
+	//Static variables
+	private static TOP_NUM: number = 100;	//The largest number that will be multiplied
+	//Instance variables
+	private num: bigint;	//Holds the number 100!
+	private sum: number;	//The sum of the digits of num
+
+	//Functions
+	//Constructor
+	public constructor(){
+		super(`What is the sum of the digits of ${Problem20.TOP_NUM}!?`);
+		this.num = 1n;
+		this.sum = 0;
+	}
+	//Operational functions
+	//Solve the problem
+	public solve(): void{
+		//If the problem has already been solved do nothing and end the function
+		if(this.solved){
+			return;
+		}
+
+		//Start the timer
+		this.timer.start();
+
+		//Run through every number from 1 to 100 and multiply it by the current num to generate 100!
+		for(let cnt = Problem20.TOP_NUM;cnt > 1;--cnt){
+			this.num *= BigInt(cnt);
+		}
+
+		//Get a string of the number because it is easier to pull aprat the individual characters
+		let numString: string = String(this.num);
+		//Run through every character in the string, convert it back to an integer and add it to the running sum
+		for(let cnt = 0;cnt < numString.length;++cnt){
+			let digit = numString.charAt(cnt);
+			this.sum += parseInt(digit);
+		}
+
+		//Stop the timer
+		this.timer.stop();
+
+		//Throw a flag to show the problem is solved
+		this.solved = true;
+	}
+	//Reset the problem so it can be run again
+	public reset(): void{
+		super.reset();
+		this.num = 1n;
+		this.sum = 0;
+	}
+	//Gets
+	//Returns the result of solving the problem
+	public getResult(): string{
+		if(!this.solved){
+			throw new Unsolved();
+		}
+		return `${Problem20.TOP_NUM}! = ${this.num}\nThe sum of the digits is: ${this.sum}`;
+	}
+	//Returns the number 100!
+	public getNumber(): bigint{
+		//If the problem hasn't been solved throw an exception
+		if(!this.solved){
+			throw new Unsolved();
+		}
+		return this.num;
+	}
+	//Returns the number 100! in a string
+	public getNumberString(): string{
+		//If the problem hasn't been solved throw an exception
+		if(!this.solved){
+			throw new Unsolved();
+		}
+		return this.num.toString();
+	}
+	//Returns the sum of the digits of 100!
+	public getSum(): number{
+		//If the porblem hasn't been solved throw an exception
+		if(!this.solved){
+			throw new Unsolved();
+		}
+		return this.sum;
+	}
+}
+
+/* Results:
+100! = 93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000
+The sum of the digits is: 648
+It took an average of 84.320 microseconds to run this problem through 100 iterations
+*/