int main() {
// The leftmost digit has to be 2, 3, 5, or 7
// The rightmost digit has to be 3 or 7
// Sieve of Erathosthenes to find primes below 1000000
int p = 2, multiple, len, sum = 0, count = 0;
while (count != NUM_PRIMES) {
if (number[p] == 0) {
number[p] = 2;
len = numLength(p);
if ((len > 1) && (truncLtoR(p,len) > 0) && (truncRtoL(p,len) > 0)) {
sum += p;
count++;
}
multiple = p * 2;
while (multiple < MAX) {
number[multiple] = 1;
multiple += p;
}
}
p++;
}
printf("%d\n", sum);
}
std::vector<int> intToVec(int n) {
std::vector<int> retVec;
auto lenN = numLength(n);
retVec.reserve(lenN);
for (int i = 0; i < lenN; ++i) {
retVec.push_back(n % 10);
n /= 10;
}
return retVec;
}
/* Converts num into a '\0' ended string in str parameter*/
void intToString(char* str, int num) {
int length = numLength(num);
int numLength = length;
int i;
if (num < 0) {
str[length - 1] = '-';
num *= -1;
numLength--;
}
for (i = 0; i < numLength; i++) {
str[i] = (char)(num % 10 + '0');
num /= 10;
}
reverseCharArray(str, length);
str[length] = '\0';
}
