Submission #236668

#	Time	Username	Problem	Language	Result	Execution time	Memory
236668		VEGAnn	Sažetak (COCI17_sazetak)	C++14	160 / 160	8 ms	384 KiB

sazetak

#include <bits/stdc++.h>
#define pll pair<ll,ll>
#define ft first
#define sd second
#define MP make_pair
using namespace std;
typedef long long ll;
const int M = 10;
const ll MX = ll(2e9);
ll ans = 0, n, m, a[M];

ll lcm(ll x, ll y){
    return min(MX, x * y / __gcd(x, y));
}

pll inv(ll a, ll b){
    if (a == 0)
        return MP(0, 1);
    else {
        pll old = inv(b % a, a);
        return MP(old.sd - (b / a) * old.ft, old.ft);
    }
}

pll calc(ll fi, ll se){
    if (__gcd(fi, se) > 1) return MP(-1, -1);

    ll ap = inv(fi, se).sd;

    ap %= fi;
    if (ap < 0) ap += fi;

    return MP(ap * se, fi * se);
}

void rec(int nm, ll fi, ll se, ll par){
    if (nm == m){
        if (fi == 1 || se == 1) return;

        pll res = calc(fi, se);

        if (res.ft < 0) return;

        if (n - 1 < res.ft) return;

        ans += par * ((n - 1 - res.ft) / res.sd + 1);

        return;
    }

    rec(nm + 1, fi, se, par);
    rec(nm + 1, lcm(fi, a[nm]), se, -par);
    rec(nm + 1, fi, lcm(se, a[nm]), -par);
}

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);

#ifdef _LOCAL
    freopen("in.txt","r",stdin);
#endif // _LOCAL

    cin >> n >> m;

    for (int i = 0; i < m; i++)
        cin >> a[i];

    for (int i = 0; i < m; i++)
        if ((n - 1) % a[i] == 0)
            ans = 1;

    rec(0, 1, 1, 1);

    cout << ans;

    return 0;
}

• Subtask 1: 160 / 160