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ProjectEulerTS/Problems/Problem20.ts

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TypeScript

//ProjectEulerTS/Problems/Problem20.ts
//Matthew Ellison
// Created: 04-07-21
//Modified: 07-14-21
//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 { 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 ${Problem20.TOP_NUM}!?`);
this.num = 1n;
this.sum = 0;
}
//Operational functions
//Solve the problem
public solve(): void{
//If the problem has already been solved do nothing and end the function
if(this.solved){
return;
}
//Start the timer
this.timer.start();
//Run through every number from 1 to 100 and multiply it by the current num to generate 100!
for(let cnt = Problem20.TOP_NUM;cnt > 1;--cnt){
this.num *= BigInt(cnt);
}
//Get a string of the number because it is easier to pull aprat the individual characters
let numString: string = String(this.num);
//Run through every character in the string, convert it back to an integer and add it to the running sum
for(let cnt = 0;cnt < numString.length;++cnt){
let digit = numString.charAt(cnt);
this.sum += parseInt(digit);
}
//Stop the timer
this.timer.stop();
//Throw a flag to show the problem is solved
this.solved = true;
}
//Reset the problem so it can be run again
public reset(): void{
super.reset();
this.num = 1n;
this.sum = 0;
}
//Gets
//Returns the result of solving the problem
public getResult(): string{
this.solvedCheck("result");
return `${Problem20.TOP_NUM}! = ${this.num}\nThe sum of the digits is: ${this.sum}`;
}
//Returns the number 100!
public getNumber(): bigint{
this.solvedCheck("number");
return this.num;
}
//Returns the number 100! in a string
public getNumberString(): string{
this.solvedCheck("number as a string");
return this.num.toString();
}
//Returns the sum of the digits of 100!
public getSum(): number{
this.solvedCheck("sum of the digits");
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
*/