BOJ 17554 - City of Lights [C++]

문제

링크

풀이

#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;
 
void solve(void) {
  int n; cin >> n;
  int k; cin >> k;
 
  int ans = 0;
  vector<bool> v(n+1, true);
  while (k--) {
    int a; cin >> a;
    for (int i=a; i<=n; i+=a) v[i] = !v[i];
    ans = max<int>(ans, count(v.begin(), v.end(), false));
  }
  cout << ans;
}
 
int main(void) {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
 
  solve();
  return 0;
}