Cod sursa(job #2015220)

Utilizator Stefan_RaduStefan Radu Stefan_Radu Data 25 august 2017 15:25:08
Problema Principiul includerii si excluderii Scor 30
Compilator cpp Status done
Runda Arhiva educationala Marime 1.44 kb
#include <fstream>
#include <vector>
#include <cmath>
#include <bitset>

using namespace std;

ifstream cin("pinex.in");
ofstream cout("pinex.out");

const int MAX = 10000;

int Era(vector < int > &primes) {
  int cnt = 0;  
  bitset < MAX > used;

  for (int i = 2; i <= MAX; i ++) {
    if (used[i]) continue;
    primes[++ cnt] = i;
    for (int j = i + i; j <= MAX; j += i) {
      used[j] = true;
    }
  }

  return cnt;
}

void solve(long long a, int cur, int MAX, long long aux, vector < int > &sol, vector < long long > &primes, long long &ans) {
  if (cur > MAX) return;

  int lim = 0;
  if (sol.size()) {
    lim = sol.back();
  }

  if (lim == MAX) return;

  for (int i = lim + 1; i <= MAX; i ++) {
    aux *= primes[i];
    if (cur % 2 == 0) {
      ans -= (a / aux);
    }
    else {
      ans += (a / aux);
    }
    sol.push_back(i);
    solve(a, cur + 1, MAX, aux, sol, primes, ans);
    sol.pop_back();
    aux /= primes[i];
  }
}

int main() {
  int n;
  cin >> n;

  vector < int > primes (MAX);
  int cnt = Era(primes);

  while (n --) {
    long long a, b;
    cin >> a >> b;
    vector < long long > prime_div(MAX);
    
    long long d = 2;
    int nr = 0;
    
    for (int i = 1; i <= cnt; i ++) {
      if (primes[i] > b) break;

      if (b % primes[i] == 0) {
        prime_div[++ nr] = primes[i];
      }
    }

    vector < int > sol;
    long long ans = 0;

    solve(a, 1, nr, 1, sol, prime_div, ans);
    cout << a - ans << '\n';
  }
}