Submission #684145

#	Time	Username	Problem	Language	Result	Execution time	Memory
684145		sharaelong	Carnival Tickets (IOI20_tickets)	C++17	100 / 100	1287 ms	114988 KiB

tickets

#include "tickets.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;

ll find_maximum(int k, vector<vector<int>> x) {
	int n = x.size();
	int m = x[0].size();
    vector<int> max_val_cnt(n, 0);
    priority_queue<pii> pq;
    for (int i=0; i<n; ++i) {
        for (int j=0; j<k; ++j) {
            pq.push({ x[i][k-1-j] + x[i][m-1-j], i });
        }
    }
    for (int i=0; i<n*k/2; ++i) {
        auto[_, idx] = pq.top();
        pq.pop();
        max_val_cnt[idx]++;
    }

    vector<pii> effective_tickets;
    for (int i=0; i<n; ++i) {
        for (int j=0; j<max_val_cnt[i]; ++j) effective_tickets.push_back({ m-1-j, i });
        for (int j=0; j<k-max_val_cnt[i]; ++j) effective_tickets.push_back({ j, i });
    }
    sort(effective_tickets.begin(), effective_tickets.end(), [&](const pii& a, const pii& b) {
        return x[a.second][a.first] < x[b.second][b.first];
    });

    ll ans_val = 0;
    vector<vector<int>> ans(n, vector<int>(m, -1));
    vector<vector<int>> plus_elem(n);
    vector<vector<int>> minus_elem(n);
	for (int i=0; i<n*k/2; ++i) {
        auto[j, idx] = effective_tickets[i];
        ans_val -= x[idx][j];
        minus_elem[idx].push_back(j);
        auto[j2, idx2] = effective_tickets[n*k-1-i];
        ans_val += x[idx2][j2];
        plus_elem[idx2].push_back(j2);
    }
    for (int i=0; i<k; ++i) {
        vector<pii> plus_freq;
        for (int j=0; j<n; ++j) plus_freq.push_back({ plus_elem[j].size(), j });
        sort(plus_freq.begin(), plus_freq.end());

        for (int j=0; j<n/2; ++j) {
            int idx = plus_freq[j].second;
            ans[idx][minus_elem[idx].back()] = i;
            minus_elem[idx].pop_back();
        }
        for (int j=n/2; j<n; ++j) {
            int idx = plus_freq[j].second;
            ans[idx][plus_elem[idx].back()] = i;
            plus_elem[idx].pop_back();
        }
    }
	allocate_tickets(ans);
	return ans_val;
}

• Subtask 1: 11 / 11
• Subtask 2: 16 / 16
• Subtask 3: 14 / 14
• Subtask 4: 14 / 14
• Subtask 5: 12 / 12
• Subtask 6: 23 / 23
• Subtask 7: 10 / 10