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105 lines
3.2 KiB
C++
105 lines
3.2 KiB
C++
//ProjectEuler/C++/Source/Problem4.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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//Find the largest palindrome made from the product of two 3-digit numbers
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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 <string>
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#include <sstream>
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#include <algorithm>
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#include "Stopwatch.hpp"
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#include "../Headers/Problem.hpp"
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#include "../Headers/Problem4.hpp"
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int Problem4::START_NUM = 100;
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int Problem4::END_NUM = 999;
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Problem4::Problem4() : Problem("Find the largest palindrome made from the product of two 3-digit numbers."){
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}
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void Problem4::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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//Start the timer
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timer.start();
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//Start at the first 3-digit number and check every one up to the last 3-digit number
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for(int firstNum = START_NUM;firstNum <= END_NUM;++firstNum){
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//You can start at the location of the first number because everything before that has already been tested. (100*101 == 101*100)
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for(int secondNum = firstNum;secondNum < END_NUM;++secondNum){
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//Get the product
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uint64_t product = firstNum * secondNum;
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//Change the number to a string
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std::string productString= std::to_string(product);
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//Reverse the string
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std::string revProductString = productString;
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std::reverse(revProductString.begin(), revProductString.end());
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//If the number and it's reverse are the same it is a palindrome so add it to the vector
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if(productString == revProductString){
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palindromes.push_back(product);
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}
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//If it's not a palindrome ignore it and move to the next number
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}
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}
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//Sort the palindromes so that the last one is the largest
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std::sort(palindromes.begin(), palindromes.end());
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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 Problem4::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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//Print the results
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std::stringstream results;
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results << "The largest palindrome is " << *(palindromes.end() - 1);
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return results.str();
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}
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std::vector<uint64_t> Problem4::getPalindromes() 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 palindromes;
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}
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uint64_t Problem4::getLargestPalindrome() 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 *(palindromes.end() - 1);
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}
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