Submission #678243

#	Time	Username	Problem	Language	Result	Execution time	Memory
678243		stanislavpolyn	Diversity (CEOI21_diversity)	C++17	64 / 100	72 ms	7924 KiB

diversity

#include <bits/stdc++.h>

#define fr(i, a, b) for (int i = (a); i <= (b); ++i)
#define rf(i, a, b) for (int i = (a); i >= (b); --i)
#define fe(x, y) for (auto& x : y)

#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define mt make_tuple

#define all(x) (x).begin(), (x).end()
#define pw(x) (1LL << (x))
#define sz(x) (int)(x).size()

using namespace std;

//mt19937_64 rng(chrono::system_clock::now().time_since_epoch().count());

mt19937_64 rng(228);


//#ifdef LOCAL
//    #define __int128 ll
//#endif // LOCAL

#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <typename T>
using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define fbo find_by_order
#define ook order_of_key

template <typename T>
bool umn(T& a, T b) {
    return a > b ? a = b, 1 : 0;
}
template <typename T>
bool umx(T& a, T b) {
    return a < b ? a = b, 1 : 0;
}

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template <typename T>
using ve = vector<T>;

const int B = 560;

int calc(ve<int> a) {
    int ans = 0;
    fr (i, 0, sz(a) - 1) {
        set<int> s;
        fr (j, i, sz(a) - 1) {
            s.insert(a[j]);
            ans += sz(s);
        }
    }
    return ans;
}


ll calc2(ve<int> a) {
    int total = 0;
    fe (x, a) total += x;
    ll ans = 0;
    int toLeft = 0;
    ans += 1LL * sz(a) * total * (total + 1) / 2;
    fr (i, 0, sz(a) - 1) {
        int toRight = total - toLeft - a[i];
        ans -= 1LL * toLeft * (toLeft + 1) / 2;
        ans -= 1LL * toRight * (toRight + 1) / 2;
        toLeft += a[i];
    }
    return ans;
}

ll calc3Brute(ve<pii> a) {
    assert(sz(a) <= 2 * B);
    int total = 0;
    int gr = 0;
    fe (x, a) {
        total += x.fi * x.se;
        gr += x.se;
    }
    ll ans = 0;

    ans += 1LL * gr * total * (total + 1) / 2;
    int toLeft = 0;
    fe (cur, a) {
        fr (j, 1, cur.se) {
            ans -= 1LL * toLeft * (toLeft + 1) / 2;
            toLeft += cur.fi;
        }
    }
    reverse(all(a));
    toLeft = 0;
    fe (cur, a) {
        fr (j, 1, cur.se) {
            ans -= 1LL * toLeft * (toLeft + 1) / 2;
            toLeft += cur.fi;
        }
    }
    return ans;
}


ll calc3(ve<pll> a) {
    assert(sz(a) <= 2 * B);

    ll total = 0;
    ll gr = 0;
    fe (x, a) {
        total += x.fi * x.se;
        gr += x.se;
    }
    ll ans = 0;

    ans += 1LL * gr * total * (total + 1) / 2;
    ll toLeft = 0;
    fe (cur, a) {
        ll res = 0;

        res += toLeft * cur.se;
        res += cur.fi * 1LL * cur.se * (cur.se - 1) / 2;

        res += 1LL * toLeft * toLeft * cur.se;
        {
            ll t = cur.se * (cur.se - 1) / 2;
            t *= 2;
            res += t * cur.fi * toLeft;
        }

        cur.se--;
        ll sumSquares = cur.se * (cur.se + 1) * (2 * cur.se + 1) / 6;
        cur.se++;

        res += sumSquares * cur.fi * cur.fi;

        res /= 2;
        ans -= res;

        toLeft += cur.fi * cur.se;
    }
    reverse(all(a));

    toLeft = 0;
    fe (cur, a) {
        ll res = 0;

        res += toLeft * cur.se;
        res += cur.fi * 1LL * cur.se * (cur.se - 1) / 2;

        res += 1LL * toLeft * toLeft * cur.se;
        {
            ll t = cur.se * (cur.se - 1) / 2;
            t *= 2;
            res += t * cur.fi * toLeft;
        }

        cur.se--;
        ll sumSquares = cur.se * (cur.se + 1) * (2 * cur.se + 1) / 6;
        cur.se++;

        res += sumSquares * cur.fi * cur.fi;

        res /= 2;
        ans -= res;

        toLeft += cur.fi * cur.se;
    }

    return ans;
}

const int N = 3e5 + 5;

int n, q;
int a[N];

int cnt[N];

int rnd(int l, int r) {
    return rng() % (r - l + 1) + l;
}

ll solve(ve<int> a) {
    fe (x, a) cnt[x] = 0;

    fe (x, a) cnt[x]++;

    ve<pii> order;
    fe (x, a) {
        if (cnt[x]) {
            order.pb({cnt[x], x});
            cnt[x] = 0;
        }
    }
    sort(all(order));
    reverse(all(order));

    {
        ve<pii> st;
        fe (cur, order) {
            if (!sz(st) || cur.fi != st.back().fi) {
                st.pb({cur.fi, 1});
            } else {
                st.back().se++;
            }
        }
        deque<pii> d;
        bool who = 0;
        fe (x, st) {
            if (x.se > 1) {
                d.push_front({x.fi, x.se / 2});
                d.pb({x.fi, x.se / 2});
                x.se %= 2;
            }
            if (x.se) {
                if (who == 0) {
                    if (sz(d) && d.front().fi == x.fi) d.front().se++;
                    else d.push_front({x.fi, 1});
                } else {
                    if (sz(d) && d.back().fi == x.fi) d.back().se++;
                    else d.pb({x.fi, 1});
                }
                who ^= 1;
            }
        }

        ve<pll> v;
        ve<pii> v2;
        fe (x, d) {
            v.pb(x);
            v2.pb(x);
        }

//        cout << calc3Brute(v2) << "\n";

        return calc3(v);
    }
    assert(0);
}



int main() {
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#else
    ios::sync_with_stdio(0);
    cin.tie(0);
#endif



    cin >> n >> q;

    ve<int> v;
    fr (i, 1, n) {
        cin >> a[i];
//        a[i] = rnd(1, 100000);
        v.pb(a[i]);
    }

    sort(all(v));

    cout << solve(v) << "\n";


//    int mn = 1e9;
//    do {
//        umn(mn, calc(v));
//    } while (next_permutation(all(v)));
//
//    cout << solve(v) << " " << mn << "\n";
//
//    do {
//        if (calc(v) == mn) {
//            cout << "v: ";
//            fe (x, v) cout << x << " ";
//            cout << "\n";
//        }
//    } while (next_permutation(all(v)));


    return 0;
}

• Subtask 1: 4 / 4
• Subtask 2: 10 / 10
• Subtask 3: 8 / 8
• Subtask 4: 16 / 16
• Subtask 5: 26 / 26
• Subtask 6: 0 / 36