python/TangDou/AcWing/Math/RongChi/Test.cpp

#include <bits/stdc++.h>

using namespace std;
const int INF = 0x3f3f3f3f;
typedef long long LL;
const int N = 20;
int a[N];
int n, m;
int res;

int main() {
    scanf("%d %d", &n, &m);
    for (int i = 0; i < m; i++) scanf("%d", &a[i]);
    for (int i = 1; i < 1 << m; i++) {
        int s = 1, c = 0;
        for (int j = 0; j < m; j++)
            if (i >> j & 1) {
                if ((LL)s * a[j] > n) {
                    s = 0;
                    break;
                }
                s *= a[j];
                c++;
            }
        if (s) {
            if (c & 1)
                res += n / s;
            else
                res -= n / s;
        }
    }
    printf("%d\n", res);
    return 0;
}