PE49

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
#include <vector>
#include <algorithm>

#include "time.h"
using namespace std;

bool isPerm(int, int);

int main() {
    clock_t t1, t2;

    int temp, i, j, diff;
    vector<int> primes;
    ifstream inputFile("primes.txt");
    while(inputFile >> temp)
    {
        if(temp!=1487 && temp != 4817 && temp!=8147)
            primes.push_back(temp);
    }

    t1 = clock();

    for(i = 0; i < primes.size(); i++){
        for(j = i+1; j < primes.size(); j++){ // loop through primes
            if(isPerm(primes[i], primes[j])) // see if they are permutations
            {
                diff = primes[j]-primes[i];           // see if the next term in the sequence
                if(isPerm(primes[j], primes[j]+diff)) // is also a permutation
                    if(find(primes.begin(), primes.end(), primes[j]+diff) != primes.end()){ // see if number is a prime
                        cout << primes[i] << primes[j] << primes[j]+diff << endl;
                        t2 = clock();
                        float seconds = ((float)t2-(float)t1)/CLOCKS_PER_SEC;
                        cout << seconds << "s" << endl;
                        return 0;
                    }
            }
        }
    }
    return 0;
}

bool isPerm(int a, int b)
{
    stringstream as,bs;
    string astr, bstr;
    as << a;
    bs << b;
    astr = as.str();
    bstr = bs.str();
    sort(astr.begin(), astr.end());
    sort(bstr.begin(), bstr.end());
    return astr==bstr;
}