Submission #171303

#	Time	Username	Problem	Language	Result	Execution time	Memory
171303		emil_physmath	Gift (IZhO18_nicegift)	C++17	30 / 100	2041 ms	177724 KiB

nicegift

#include <algorithm>
#include <iostream>
#include <vector>
#include <queue>
#include <cmath>
#include <map>
#include <set>
using namespace std;
typedef double ldouble;
typedef long long llong;
const int maxN = 100001;

int n, k;
vector<llong> arr;
multiset<pair<llong, int>> a;
llong mx = -1, sum = 0;
vector<pair<llong, vector<int>>> ans;

void Subtract(multiset<pair<llong, int>>::reverse_iterator s)
{
    //cerr << "1\n";
    auto st_s = s;
    vector<int> cur;
    llong mn = s->first;
    auto it = s;
    for (; cur.size() < k; ++it)
    {
        cur.push_back(it->second);
        mn = min(mn, it->first);
    }
    int st_mn = mn;
    if (it != a.rend())
        mn = min(mn, sum / k - it->first);
    if (st_s != a.rbegin())
        mn = min(mn, sum / k - a.rbegin()->first);
    if (!mn)
        return;
    if (st_mn < mn)
    {
        auto st_it = it;
        bool itIsEnd = false;
        for (int x = 0; x < k; ++x)
        {
            if (it == a.rend())
            {
                itIsEnd = true;
                break;
            }
            ++it;
        }
        if (!itIsEnd)
        {
            Subtract(st_it);
            return;
        }
    }
    // sum / k - it->first < mn
    // sum / k < mn + it->first
    // sum / k < 2 * it->first
    // sum < k * it->first * 2
    // sum > k * it->first
    if (!mn) throw;
    // it->first <= (sum - k * mn) / k
    // k * it->first <= sum - k * mn
    // mn * k <= sum - k * it->first
    // mn <= sum / k - it->first
    /*
        mn = min(mn, a.rbegin()->first - it->first + 1);
    */
    /*
    if (!mn)
    {
        cout << -1 << endl;
        exit(0);
    }
    */
    for (int x: cur)
    {
        a.erase({arr[x], x});
        sum -= arr[x];
        a.insert({arr[x] -= mn, x});
        sum += arr[x];
    }
    ans.push_back({mn, cur});
    /*cerr << "a` ";
    for (pair<llong, int> i: a)
        cerr << i.first << ' ';
    cerr << endl;*/
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    cin >> n >> k;
    arr.resize(n);
    for (int i = 0; i < n; ++i)
    {
        cin >> arr[i];
        sum += arr[i];
        mx = max(mx, arr[i]);
        a.insert({arr[i], i});
    }
    if (sum % k || mx > sum / k)
    {
        cout << -1 << endl;
        exit(0);
    }

    while (a.rbegin()->first)
    {
        //cerr << "0\n";
        Subtract(a.rbegin());
        /*cerr << endl << ":";
        for (auto it: a)
            cerr << it.first << ' ';
        cerr << ":" << endl;*/
    }
    cout << ans.size() << '\n';
    for (auto x: ans)
    {
        cout << x.first << ' ';
        for (int y: x.second)
            cout << y + 1 << ' ';
        cout << '\n';
    }
}
// 6 5 4 3 x
// x x-1 x-2 x-3 x

Compilation message (stderr)

nicegift.cpp: In function 'void Subtract(std::multiset<std::pair<long long int, int> >::reverse_iterator)':
nicegift.cpp:26:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (; cur.size() < k; ++it)
            ~~~~~~~~~~~^~~

• Subtask 1: 7 / 7
• Subtask 2: 11 / 11
• Subtask 3: 12 / 12
• Subtask 4: 0 / 19
• Subtask 5: 0 / 51