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ProjectEulerCPP/Source/Problem20.cpp

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//ProjectEuler/C++/Source/Problem20.cpp
//Matthew Ellison
// Created: 11-07-18
//Modified: 07-14-19
//What is the sum of the digits of 100!?
//Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/myClasses
//This file contains a header from the gmp library. The library is used for large integers.
//You can find more information about them at https://gmplib.org/
//When compiling this file you need to have the gmp library installed as well as linking the libraries to your executable using the -lgmpxx and -lgmp flags
/*
Copyright (C) 2019 Matthew Ellison
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <cinttypes>
#include <string>
#include <sstream>
#include "gmpxx.h"
#include "Stopwatch.hpp"
#include "../Headers/Problem20.hpp"
Problem20::Problem20() : Problem("What is the sum of the digits of 100!?"), num(1), sum(0){
//num Starts at 1 because multiplication is performed on it
//sum starts at 0 because addition is performed on it
}
void Problem20::solve(){
//If the problem has already been solved do nothing and end the function
if(solved){
return;
}
//Start the timer
timer.start();
//Run through every number from 1 to 100 and multiply it by the current num
for(int cnt = 1;cnt <= 100;++cnt){
num *= cnt;
}
//Get a string of the number because it is easier to pull appart the individual characters
std::string numString = num.get_str();
//Run through every character in the string, convert it back to an integer and add it to the running sum
for(unsigned int cnt = 0;cnt < numString.size();++cnt){
sum += std::stoi(numString.substr(cnt, 1));
}
//Stop the timer
timer.stop();
//Throw a flag to show the problem is solved
solved = true;
}
std::string Problem20::getString() const{
//If the problem hasn't been solved throw an exception
if(!solved){
throw unsolved();
}
std::stringstream results;
//Print the results
results << "100! = " << num.get_str()
<< "\nThe sum of the digits is: " << sum;
return results.str();
}
mpz_class Problem20::getNumber() const{
//If the problem hasn't been solved throw an exception
if(!solved){
throw unsolved();
}
return num;
}
std::string Problem20::getNumberString() const{
//If the problem hasn't been solved throw an exception
if(!solved){
throw unsolved();
}
return num.get_str();
}
uint64_t Problem20::getSum() const{
//If the problem hasn't been solved throw an exception
if(!solved){
throw unsolved();
}
return sum;
}