【模板小程序】求第n个质数

#include <iostream>
#include <vector>
using namespace std;

int nth_prime(int n) {
  vector<int> primes(n);
  primes[0] = 2;
  int CntOfPrime = 1;
  for (int i = 3; CntOfPrime < n; ++i) {
    bool isPrime = true;
    for (int j = 0; j < CntOfPrime && primes[j]*primes[j] <= i; ++j) {
      if (i % primes[j] == 0) {
        isPrime = false;
        break;
      }
    }
    if (isPrime) {
      ++CntOfPrime;
      primes[CntOfPrime - 1] = i;
    }
  }
  return primes[n - 1];
}

int main() {
  int n;
  while (cin >> n) {
    cout << nth_prime(n) << endl;
  }
  return 0;
}