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72 lines
2.4 KiB
Java
72 lines
2.4 KiB
Java
//ProjectEuler/Java/Problem12.java
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//Matthew Ellison
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// Created: 03-04-19
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//Modified: 03-28-19
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//What is the value of the first triangle number to have over five hundred divisors?
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//Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/JavaClasses
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/*
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Copyright (C) 2019 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 mattrixwv.Stopwatch;
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import mattrixwv.Algorithms;
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import java.util.ArrayList;
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public class Problem12{
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private static final Long GOAL_DIVISORS = 500L; //The minimum number of divisors that you want
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public static void main(String[] argv){
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Stopwatch timer = new Stopwatch(); //Allows timing of the algorithm
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//Setup the other variables
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Boolean foundNumber = false; //TO flag whether the number has been found
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Long sum = 1L;
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Long counter = 2L; //The next number to be added to the sum to make a triangular number
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ArrayList<Long> divisors = new ArrayList<Long>();
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//Start the timer
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timer.start();
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//Loop until you find the appropriate number
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while((!foundNumber) && (sum > 0)){
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divisors = Algorithms.getDivisors(sum);
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//If the number of divisors is correct set the flag
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if(divisors.size() > GOAL_DIVISORS.intValue()){
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foundNumber = true;
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}
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//Otherwise add to the sum and increase the next number
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else{
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sum += counter;
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++counter;
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}
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}
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//Stop the timer
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timer.stop();
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//Print the results
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System.out.printf("The triangulare number %d is the sum of all numbers >= %d and has %d divisors\n", sum, counter - 1, divisors.size());
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System.out.println("It took " + timer.getStr() + " to run this algorithms");
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}
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}
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/* Results:
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The triangulare number 76576500 is the sum of all numbers >= 12375 and has 576 divisors
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It took 758.987 milliseconds to run this algorithms
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*/
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