ProjectEulerCPP/src/Problems/Problem37.cpp

//ProjectEuler/ProjectEulerCPP/src/Problems/Problem37.cpp
//Matthew Ellison
// Created: 06-30-21
//Modified: 06-30-21
//Find the sum of the only eleven primes that are both truncatable from left to right and right to left (2, 3, 5, and 7 are not counted).
//Unless otherwise listed all non-standard includes are my own creation and available from https://bibucket.org/Mattrixwv/myClasses
/*
	Copyright (C) 2021  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 <vector>
#include "Problems/Problem37.hpp"
#include "Algorithms.hpp"


//The last prime before 11 since single digit primes aren't checked
uint64_t Problem37::LAST_PRIME_BEFORE_CHECK = 7;

//Constructor
Problem37::Problem37() : Problem("Find the sum of the only eleven primes that are both truncatable from left to right and right to left (2, 3, 5, and 7 are not counted)."), sum(0){
}

//Operational functions
//Solve the problem
void Problem37::solve(){
	//If the problem has already been solved do nothing and end the function
	if(solved){
		return;
	}

	//Start the timer
	timer.start();

	//Create the sieve and get the first prime number
	mee::SieveOfEratosthenes<uint64_t> sieve;
	uint64_t currentPrime = sieve.next();
	//Loop through the sieve until you get to LAST_PRIME_BEFORE_CHECK
	while(currentPrime < LAST_PRIME_BEFORE_CHECK){
		currentPrime = sieve.next();
	}
	//Loop until truncPrimes contains 11 elements
	while(truncPrimes.size() < 11){
		bool isTruncPrime = true;
		//Get the next prime
		currentPrime = sieve.next();
		//Convert the prime to a string
		std::string primeString = std::to_string(currentPrime);
		//If the string contains an even digit move to the next prime
		for(uint64_t strLoc = 0;(strLoc < primeString.size()) && (isTruncPrime);++strLoc){
			//Allow 2 to be the first digit
			if((strLoc == 0) && (primeString[strLoc] == '2')){
				continue;
			}
			switch(primeString[strLoc]){
				case '0' :
				case '2' :
				case '4' :
				case '6' :
				case '8' : isTruncPrime = false; break;
			}
		}
		//Start removing digits from the left and see if the number stays prime
		if(isTruncPrime){
			for(uint64_t truncLoc = 1;truncLoc < primeString.size();++truncLoc){
				//Create a substring of the prime, removing the needed digits from the left
				std::string primeSubstring = primeString.substr(truncLoc);
				//Convert the string to an int and see if the number is still prime
				uint64_t newPrime = std::stoull(primeSubstring);
				if(!mee::isPrime(newPrime)){
					isTruncPrime = false;
					break;
				}
			}
		}
		//Start removing digits from the right and see if the number stays prime
		if(isTruncPrime){
			for(uint64_t truncLoc = 1;truncLoc < primeString.size();++truncLoc){
				//Create a substring of the prime, removing the needed digits from the right
				std::string primeSubstring = primeString.substr(0, primeString.size() - truncLoc);
				//Convert the string to an int and see if the number is still prime
				uint64_t newPrime = std::stoull(primeSubstring);
				if(!mee::isPrime(newPrime)){
					isTruncPrime = false;
					break;
				}
			}
		}
		//If the number remained prime through all operations add it to the vector
		if(isTruncPrime){
			truncPrimes.push_back(currentPrime);
		}
	}
	//Get the sum of all elements in the truncPrimes vector
	sum = mee::getSum(truncPrimes);

	//Stop the timer
	timer.stop();

	//Throw a flag to show the problem is solved
	solved = true;
}
//Reset the problem so it can be run again
void Problem37::reset(){
	Problem::reset();
	truncPrimes.clear();
	sum = 0;
}

//Gets
//Returns a string with the solution to the problem
std::string Problem37::getResult(){
	//If the problem hasn't been solved throw an exception
	if(!solved){
		throw Unsolved();
	}
	std::stringstream result;
	result << "The sum of all left and right truncatable primes is " << sum;
	return result.str();
}
//Returns the list of primes that can be truncated
std::vector<uint64_t> Problem37::getTruncatablePrimes(){
	//If the problem hasn't been solved throw an exception
	if(!solved){
		throw Unsolved();
	}
	return truncPrimes;
}
//Get the sum of all primes in truncPrimes
uint64_t Problem37::getSumOfPrimes(){
	//If the problem hasn't been solved throw an exception
	if(!solved){
		throw Unsolved();
	}
	return sum;
}