Submission #301536

#	Time	Username	Problem	Language	Result	Execution time	Memory
301536		kevinsogo	Carnival Tickets (IOI20_tickets)	C++17	100 / 100	1691 ms	97680 KiB

tickets

#include "tickets.h"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;

ll find_maximum(int k, vector<vector<int>> x) {
    int n = x.size();
    int m = x[0].size();
    assert(n % 2 == 0);

    vector<vector<int>> xs = x;
    vector<pair<int,int>> stones(n*k);
    ll s = 0;
    for (int i = 0; i < n; i++) {
        sort(xs[i].begin(), xs[i].end());
        for (int j = 0; j < k; j++) {
            s -= xs[i][j];
            stones.emplace_back(xs[i][m-j-1] + xs[i][k-j-1], i);
        }
    }
    vector<int> ts(n);
    sort(stones.begin(), stones.end());

    for (int it = 0; it < k*n/2; it++) {
        auto [v, i] = stones.back(); stones.pop_back();
        s += v;
        ts[i]++;
    }

    vector<vector<int>::iterator> bads(n), guds(n);
    for (int i = 0; i < n; i++) {
        bads[i] = xs[i].begin();
        guds[i] = xs[i].begin() + m - ts[i];
    }

    vector<vector<int>> roundv(n, vector<int>(k, -1));
    vector<int> rows(n);
    iota(rows.begin(), rows.end(), 0);
    for (int r = 0; r < k; r++) {
        sort(rows.begin(), rows.end(), [&](int i, int j) { return distance(guds[i], xs[i].end()) < distance(guds[j], xs[j].end()); });
        for (int idx = 0; idx < n; idx++) {
            int i = rows[idx];
            roundv[i][r] = *((idx < n/2 ? bads : guds)[i]++);
        }
    }

    vector<vector<int>> take(n, vector<int>(m, -1));
    for (int i = 0; i < n; i++) {
        assert(bads[i] == xs[i].begin() + k - ts[i]);
        assert(guds[i] == xs[i].end());
        unordered_map<int,vector<int>> inds;
        for (int j = 0; j < m; j++) {
            inds[x[i][j]].push_back(j);
        }
        for (int r = 0; r < k; r++) {
            int v = roundv[i][r];
            take[i][inds[v].back()] = r; inds[v].pop_back();
        }
    }

    allocate_tickets(take);
    return s;
}

• 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