Submission #3972294

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

int f(vector<int>& C) {
  int N = C.size();
  vector<bool> T(N, true);
  for (int i = 0; i < N-1; i++) {
    for (int j = i+1; j < N; j++) {
      if (C[j] % C[i] == 0) T[j] = !T[j];
    }
  }
  int ans = 0;
  for (auto t : T) ans += t;
  return ans;
}

int main() {
  int N;
  cin >> N;
  vector<int> C(N);
  for (int& c : C) cin >> c;
  long s = 0, n = 0;
  do {
    s += f(C);
    n++;
  } while(next_permutation(C.begin(), C.end()));
  printf("%.15f\n", s / (double)n);
}

Submission Info

Judge Result