Submission #4026019

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Source Code Expand

// includes
#include <cstdio>
#include <cstdint>
#include <iostream>
#include <iomanip>
#include <string>
#include <queue>
#include <stack>
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <algorithm>
#include <utility>
#include <functional>
#include <cmath>
#include <climits>
#include <bitset>

// macros
#define ll long long int
#define pb push_back
#define mk make_pair
#define pq priority_queue
#define FOR(i, a, b) for(int i=(a); i<(b);++i)
#define rep(i, n) FOR(i, 0, n)

using namespace std;

//  types
typedef pair<int, int> P;
typedef pair<ll, int> Pl;
typedef pair<ll, ll> Pll;
typedef pair<double, double> Pd;
 
// constants
const int inf = 1e9;
const ll linf = 1LL << 50;
const double EPS = 1e-10;

// solve
ll gcd(ll x, ll y){
  if(x > y)return gcd(y, x);
  if(x == 0)return y;
  return gcd(y%x, x);
}

int main(int argc, char const* argv[])
{
  int n;
  ll k;
  cin >> n >> k;
  vector<ll> a(n);
  rep(i, n)cin >> a[i];

  vector<ll> kvec;
  for(ll i = 2; i * i <= k; i++){
    if(k % i == 0){
      kvec.pb(i);
      if(i * i != k)kvec.pb(k / i);
    }
  }
  kvec.pb(1);
  kvec.pb(k);
  sort(kvec.begin(), kvec.end());
  kvec.erase(unique(kvec.begin(), kvec.end()), kvec.end());

  unordered_map<ll, int> mp;
  rep(i, n)mp[gcd(k, a[i])]++;
  rep(i, kvec.size()){
    FOR(j, i+1, kvec.size()){
      if(kvec[j] % kvec[i] == 0)mp[kvec[i]] += mp[kvec[j]];
    }
  }

  ll res = 0;
  rep(i, n){
    ll tmp = k / gcd(k, a[i]);
    res += mp[tmp];
    if(gcd(k, a[i]) % tmp == 0)res--;
  }
  cout << res / 2 << endl;
	return 0;
}

Submission Info

Judge Result