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95 lines
2.9 KiB
C++
95 lines
2.9 KiB
C++
//ProjectEuler/C++/Source/Problem5.cpp
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//Matthew Ellison
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// Created: 09-28-18
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//Modified: 07-14-19
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//What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20?
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//Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/myClasses
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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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#include <vector>
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#include <cinttypes>
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#include <string>
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#include <sstream>
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#include "Stopwatch.hpp"
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#include "../Headers/Problem.hpp"
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#include "../Headers/Problem5.hpp"
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Problem5::Problem5() : Problem("What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20?"), smallestNum(0){
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}
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void Problem5::solve(){
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//If the problem has already been solved do nothing and end the function
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if(solved){
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return;
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}
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//Setup your variables
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bool numFound = false; //Used to determine if the number has been found
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//Start the timer
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timer.start();
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//Start at 20 because it must at least be divisible by 20. Increment by 2 because it must be an even number to be divisible by 2
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//Loop through every even number starting at 20
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int currentNum = 20;
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while((currentNum > 0) && (!numFound)){
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//Start by assuming you found the number (because we throw a flag if we didn't find it)
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numFound = true;
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//Step through every number from 1-20 seeing if the current number is divisible by it
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for(int divisor = 1;divisor <= 20;++divisor){
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//If it is not divisible then throw a flag and start looking at the next number
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if((currentNum % divisor) != 0){
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numFound = false;
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break;
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}
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}
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//If you didn't find the correct number then increment by 2
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if(!numFound){
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currentNum += 2;
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}
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}
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smallestNum = currentNum;
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//Stop the timer
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timer.stop();
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//Throw a flag to show the problem is solved
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solved = true;
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}
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std::string Problem5::getString() const{
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//If the problem hasn't been solved throw an exception
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if(!solved){
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throw unsolved();
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}
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std::stringstream results;
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results << "The smallest positive number evenly divisible by all numbers 1-20 is " << smallestNum;
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return results.str();
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}
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int Problem5::getNumber() const{
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//If the problem hasn't been solved throw an exception
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if(!solved){
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throw unsolved();
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}
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return smallestNum;
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}
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