A mutating algorithm to find a string

dawkins.cpp

#include <iostream>
#include <string>
#include <ctime>
#include <vector>
#include <algorithm>
#include <unistd.h>

const static std::string magic = "METHINKS IT IS LIKE A WEASEL";


char getRandomLetter() {

        char res = (rand()%('Z' - '@')) + '@';
        return res=='@'?' ':res;

}

int chance = 5;

bool doWeMutate() {
        int randomNumber = rand()%chance;
        return randomNumber % chance == 0;
}

int howManyStringsMatched(const std::string& toTest) {
        int num = 0;
        for(int i=0; i<magic.size(); ++i) {
                if(magic[i] == toTest[i])
                        ++num;
        }
        return num;
}

int main(int argc, char** argv) {


        if(argc != 2 || atoi(argv[1]) == 0) {
                std::cout<<" 1 paramter plox."<<std::endl;
                return 1;
        }

        chance = atoi(argv[1]);

        std::cout<<"running with mutation chance of 1/"<<chance<<std::endl;

        srand(time(0));

        std::string starting;
        starting.reserve(28);

        for(int i=0; i<28; ++i) {
                starting.push_back(getRandomLetter());
        }

        for(;;) {


                std::vector<std::string> mutations;
                mutations.reserve(100);
                for(int i=0; i<100; ++i) {
                        std::string currentString = starting;

                        for(int j=0; j<currentString.size(); ++j) {
                                if(currentString[j] != magic[j] && doWeMutate())
                                        currentString[j] = getRandomLetter();
                        }
                        mutations.push_back(std::move(currentString));
                }

                const auto iterator = std::max_element(mutations.begin(), mutations.end(), [](const std::string& lhs, const std::string& rhs) {
                                return howManyStringsMatched(lhs) < howManyStringsMatched(rhs);
                });

                starting = std::move(*iterator);

                if(starting == magic) {
                        break;
                }
        }

        std::cout<<"got magic"<<std::endl;
}