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67 lines
2.4 KiB
Java
67 lines
2.4 KiB
Java
//ProjectEuler/Java/Problem19.java
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//Matthew Ellison
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// Created: 03-14-19
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//Modified: 03-28-19
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//What is the sum of the digits of 100!?
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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 java.math.BigInteger;
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public class Problem20{
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private static Integer TOP_NUM = 100;
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public static void main(String[] argv){
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Stopwatch timer = new Stopwatch();
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BigInteger num = new BigInteger("1"); //The number that is being generated
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Long sum = 0L; //The sum of the digits of num
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//Start the timer
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timer.start();
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//Run through every number from 1 to 100 and multiply it by the current num to generate 100!
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for(Integer cnt = TOP_NUM;cnt > 1;--cnt){
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num = num.multiply(BigInteger.valueOf(cnt));
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}
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//Get a string of the number because it is easier to pull appart the individucal characters
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String numString = num.toString();
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//Run through every character in the string, convert it back to an integer and add it to the running sum
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for(Integer cnt = 0;cnt < numString.length();++cnt){
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Character temp = numString.charAt(cnt);
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sum += Integer.valueOf(temp.toString());
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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("%d! = %s\n", TOP_NUM, num.toString());
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System.out.printf("The sum of the digits is: %d\n", sum);
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System.out.println("It took " + timer.getStr() + " to run this algorithm");
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}
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}
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/* Restuls:
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100! = 93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000
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The sum of the digits is: 648
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It took 2.667 milliseconds to run this algorithm
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*/
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