Submission #171308

#	Time	Username	Problem	Language	Result	Execution time	Memory
171308		emil_physmath	Gift (IZhO18_nicegift)	C++17	100 / 100	1389 ms	102676 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 main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int n, k;
    cin >> n >> k;
    vector<llong> arr(n);
    priority_queue<pair<llong, int>> a;
    llong mx = -1, sum = 0;
    for (int i = 0; i < n; ++i)
    {
        cin >> arr[i];
        sum += arr[i];
        mx = max(mx, arr[i]);
        a.push({arr[i], i});
    }
    if (sum % k || mx > sum / k)
    {
        cout << -1 << endl;
        exit(0);
    }
    vector<pair<llong, vector<int>>> ans;
    while (a.top().first)
    {
        vector<int> cur;
        llong mn = a.top().first;
        while (cur.size() < k)
        {
            cur.push_back(a.top().second);
            mn = min(mn, a.top().first);
            a.pop();
        }
        if (!a.empty())
            mn = min(mn, sum / k - a.top().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.push({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;*/
    }
    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 'int main()':
nicegift.cpp:40:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         while (cur.size() < k)
                ~~~~~~~~~~~^~~

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