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Added solution to problem 37
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169
Problems/Problem37.ts
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169
Problems/Problem37.ts
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//ProjectEulerTS/Problems/Problem37.ts
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//Matthew Ellison
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// Created: 07-01-21
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//Modified: 07-01-21
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//Find the sum of the only eleven primes that are both truncatable from left to right and right to left (2, 3, 5, and 7 are not counted).
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//Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/typescriptClasses
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/*
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Copyright (C) 2021 Matthew Ellison
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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import { getSum, isPrime, sieveOfEratosthenes } from "../../../Typescript/typescriptClasses/Algorithms";
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import { Unsolved } from "../Unsolved";
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import { Problem } from "./Problem";
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export class Problem37 extends Problem{
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//Variables
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//Static variables
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private static LAST_PRIME_BEFORE_CHECK: number = 7; //The last prime before 11 since signle digit primes aren't checked
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//Instance variables
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private truncPrimes: number[];
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private sum: number;
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//Functions
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//Constructor
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public constructor(){
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super("Find the sum of the only eleven primes that are both truncatable from left to right and right to left (2, 3, 5, and 7 are not counted).");
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this.truncPrimes = [];
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this.sum = 0;
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}
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//Operational functions
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//Solve the problems
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public solve(): void{
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//If the porblem has already been solved do nothing and end the function
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if(this.solved){
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return;
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}
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//Start the timer
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this.timer.start();
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//Create the sieve and get the first prime number
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let sieve = sieveOfEratosthenes();
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let tempPrime = sieve.next().value;
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let currentPrime: number = 0;
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if(typeof tempPrime == "number"){
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currentPrime = tempPrime;
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}
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else{
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throw new Unsolved("Sieve overflowed")
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}
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while(currentPrime < Problem37.LAST_PRIME_BEFORE_CHECK){
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tempPrime = sieve.next().value;
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if(typeof tempPrime == "number"){
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currentPrime = tempPrime;
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}
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else{
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throw new Unsolved("Sieve overflowed")
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}
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}
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//Loop until truncPrimes contains 11 elements
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while(this.truncPrimes.length < 11){
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let isTruncPrime: boolean = true;
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//Get the next prime
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tempPrime = sieve.next().value;
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if(typeof tempPrime == "number"){
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currentPrime = tempPrime;
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}
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else{
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throw new Unsolved("Sieve overflowed")
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}
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//Conver the prime to a string
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let primeString: string = currentPrime.toString();
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//If the string contains an even digit move to the next prime
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for(let strLoc = 0;(strLoc < primeString.length) && (primeString[strLoc] == '2');++strLoc){
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//Allow 2 to be the first digit
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if((strLoc == 0) && (primeString[strLoc] == '2')){
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continue;
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}
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if((primeString[strLoc] == '0') || (primeString[strLoc] == '2') || (primeString[strLoc] == '4') || (primeString[strLoc] == '6') || (primeString[strLoc] == '8')){
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isTruncPrime = false;
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break;
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}
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}
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//Start removing digits from the left and see if the number stays prime
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if(isTruncPrime){
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for(let truncLoc = 1;(truncLoc < primeString.length) && (isTruncPrime);++truncLoc){
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//Create a substring of the prime, removing the needed digits from the left
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let primeSubstring: string = primeString.substring(truncLoc);
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//Convert the string to an int and see if the number is still prime
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let newPrime: number = parseInt(primeSubstring);
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if(!isPrime(newPrime)){
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isTruncPrime = false;
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}
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}
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}
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//Start removing digits from the right and see if the number stays prime
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if(isTruncPrime){
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for(let truncLoc = 1;(truncLoc < primeString.length) && (isTruncPrime);++truncLoc){
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//Create a substring of the prime, removing the needed digits from the right
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let primeSubstring: string = primeString.substring(0, primeString.length - truncLoc);
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//Convert the string to an int and see if the number is still prime
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let newPrime: number = parseInt(primeSubstring);
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if(!isPrime(newPrime)){
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isTruncPrime = false;
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}
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}
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}
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//If the number remained prime through all operations add it to the vector
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if(isTruncPrime){
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this.truncPrimes.push(currentPrime);
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}
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}
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//Get the sum of all elements in the truncPrimes list
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this.sum = getSum(this.truncPrimes);
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//Stop the timer
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this.timer.stop();
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//Throw a flag to show the problem is solved
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this.solved = true;
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}
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//Reset the problem so it can be run again
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public reset(): void{
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super.reset();
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this.truncPrimes = [];
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this.sum = 0;
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}
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//Gets
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//Returns a string with the solution to the problem
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public getResult(): string{
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//If the problem hasn't been solve dthrow an exception
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if(!this.solved){
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throw new Unsolved();
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}
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return `The sum of all left and right truncatable primes is ${this.sum}`;
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}
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//Returns the list of primes that can be truncated
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public getTruncatablePrimes(): number[]{
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if(!this.solved){
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throw new Unsolved();
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}
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return this.truncPrimes;
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}
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//Returns the sum of all elements in truncPrimes
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public getSumOfTruncatablePrimes(): number{
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if(!this.solved){
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throw new Unsolved();
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}
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return this.sum;
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}
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}
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/* Results:
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The sum of all left and right truncatable primes is 748317
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It took an average of 104.007 milliseconds to run this problem through 100 iterations
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*/
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