int main(int argc, char **args) {
Q_UNUSED(argc);
Q_UNUSED(args);
Primes *primes = newPrimes();
int i = 0;
int p1;
int dmul;
int p2mul;
int d;
qint64 sum = 0;
for (int p2 = 7; p2 <= 1000003; p2 += 2) { /* last p2 == 1000003*/
updatePrimes(p2, primes);
if (isPrime(p2, *primes) == false) continue;
i += 1;
p1 = primes->l[primes->s[p2] - 1];
d = pow(10, floor(log10(p1))+1);
Q_ASSERT(d > p1 && p1*10 > d);
int t = extendedEuclid(d, p2, &dmul, &p2mul);
Q_ASSERT(t == 1);
Q_ASSERT((qint64) d * (qint64) dmul + (qint64) p2 * (qint64) p2mul == 1);
qint64 x = (qint64) -p1 * (qint64) dmul;
while (x < 0) {
x += p2;
}
x = (x + p2) % p2;
qint64 wantedNumber = (qint64)x * (qint64)d + p1;
Q_ASSERT(wantedNumber > p1 && wantedNumber > p2);
Q_ASSERT(wantedNumber % p2 == 0);
Q_ASSERT((wantedNumber - p1) % d == 0);
if (i % 1000 == 0 || p2 > 998999 || p2 < 200) {
qDebug() << QString("%1 %2: %3 % %4 == 0").arg(p1, 7).arg(p2, 7).arg(wantedNumber, 20).arg(p2, 7);
}
sum += wantedNumber;
Q_ASSERT(sum > 0);
}
qDebug() << sum;
deletePrimes(primes);
return 0;
}
void extendedEuclid(int a, int b) {
if(b == 0) {
d = a;
x = 1;
y = 0;
} else {
extendedEuclid(b, a % b);
int tmp = x;
x = y;
y = tmp - (a / b) * y;
}
}
long mod_inverse( long base, long m) {
long d, x, y;
long retValue = 0;
d = 1;
x = 1;
y = 1;
if(GCD(base, m) == 1) {
extendedEuclid( base, m, &x, &y, &d);
retValue = x;
if(retValue < 0) { retValue = retValue + m;}
return retValue;
}
return -1;
}
// returns greatest common divisor of a, b
static int extendedEuclid(int a, int b, int *amul, int *bmul) {
if (a > b) {
int t1 = a; a = b; b = t1;
int *t2 = amul; amul = bmul; bmul = t2;
}
if (b % a == 1) {
*bmul = 1;
*amul = -(b/a);
return 1;
}
int ret = extendedEuclid(b % a, a, amul, bmul);
int t = *bmul;
*bmul = *amul;
*amul = t + *amul * -(b/a);
return ret;
}
int modularInverse(int a, int n)
{
pii ret = extendedEuclid(a, n);
return ((ret.x % n) + n) % n;
}
int modInverse(int a, int m) {
extendedEuclid(a, m);
return (x % m + m) % m;
}
