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110 lines
3.5 KiB
TypeScript
110 lines
3.5 KiB
TypeScript
//ProjectEulerTS/Problems/Problem4.ts
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//Matthew Ellison
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// Created: 10-24-20
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//Modified: 07-14-21
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//Find the largest palindrome made from the product of two 3-digit numbers
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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 { Problem } from "./Problem";
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export class Problem4 extends Problem{
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//Variables
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//Static variables
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private static START_NUM: number = 100; //The first number to be multiplied
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private static END_NUM: number = 999; //The last number to be multiplied
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//Instance variables
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private palindromes: number[]; //Holds all number that turn out to be palindromes
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//Constructor
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public constructor(){
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super("Find the largest palindrome made from the product of two 3-digit numbers");
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}
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//Operational functions
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//Solve the problem
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public solve(): void{
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//If the problem 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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//Start at the first 3-digit number and check every one up to the last 3-digit number
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for(let firstNum: number = Problem4.START_NUM;firstNum <= Problem4.END_NUM;++firstNum){
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//You can start at the location of the first number because everything before that has already been tested. (100 * 101 == 101 * 100)
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for(let secondNum = firstNum;secondNum < Problem4.END_NUM;++secondNum){
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//Get the product
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let product: number = firstNum * secondNum;
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//Change the number into a string
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let productString: string = product.toString();
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//Reverse the string
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let reverseString: string = productString.split("").reverse().join("");
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//If the number and it's reverse are the same it is a palindrome so add it to the list
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if(productString == reverseString){
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this.palindromes.push(product);
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}
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//If it's not a palindrome ignore it and move to the next number
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}
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}
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//Sort the palindromes so that the last one is the largest
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this.palindromes = this.palindromes.sort((n1, n2) => n1 - n2);
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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.palindromes = [];
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}
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//Gets
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//Returns the result of solving the problem
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public getResult(): string{
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this.solvedCheck("result");
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return `The largest palindrome is ${this.palindromes[this.palindromes.length - 1]}`;
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}
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//Returns the list of all palindromes
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public getPalindromes(): number[]{
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this.solvedCheck("palindromes");
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return this.palindromes;
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}
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//Returns the largest palindrome
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public getLargestPalindrome(): number{
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this.solvedCheck("largest palindrome");
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return this.palindromes[this.palindromes.length - 1];
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}
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}
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/* Results:
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The largest palindrome is 906609
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It took an average of 121.130 milliseconds to run this problem through 100 iterations
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*/
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