Submission #769156

#	Time	Username	Problem	Language	Result	Execution time	Memory
769156		t6twotwo	Carnival Tickets (IOI20_tickets)	C++17	41 / 100	610 ms	71368 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();
    if (M == 1) {
        allocate_tickets(vector(N, vector{0}));
        vector<int> v(N);
        for (int i = 0; i < N; i++) {
            v[i] = x[i][0];
        }
        sort(v.begin(), v.end());
        ll s = 0;
        for (int i = 0; i < N; i++) {
            s += abs(v[N / 2] - v[i]);
        }
        return s;
    }
    if (K == 1) {
        vector dp(N + 1, vector<ll>(N / 2 + 1, -1e18));
        dp[0][0] = 0;
        for (int i = 0; i < N; i++) {
            for (int j = 0; j <= N / 2; j++) {
                if (j < N / 2) {
                    dp[i + 1][j + 1] = dp[i][j] + x[i][M - 1];
                }
                dp[i + 1][j] = max(dp[i + 1][j], dp[i][j] - x[i][0]);
            }
        }
        vector a(N, vector<int>(M, -1));
        for (int i = N - 1, j = N / 2; i >= 0; i--) {
            if (dp[i][j] - x[i][0] == dp[i + 1][j]) {
                a[i][0] = 0;
            } else {
                a[i][M - 1] = 0;
                j--;
            }
        }
        allocate_tickets(a);
        return dp[N][N / 2];
    }
    if (K == M) {
        vector<tuple<int, int, int>> v;
        for (int i = 0; i < N; i++) {
            for (int j = 0; j < M; j++) {
                v.emplace_back(x[i][j], i, j);
            }
        }
        sort(v.begin(), v.end());
        vector f(N, vector<bool>(M));
        ll ans = 0;
        for (int i = 0; i < N * M / 2; i++) {
            auto [t, x, y] = v[i];
            ans -= t;
        }
        for (int i = N * M / 2; i < N * M; i++) {
            auto [t, x, y] = v[i];
            ans += t;
            f[x][y] = 1;
        }
        vector a(N, vector<int>(M));
        int x = 0, y = K - 1;
        for (int i = 0; i < N; i++) {
            for (int j = 0; j < M; j++) {
                if (!f[i][j]) {
                    a[i][j] = y--;
                } else {
                    a[i][j] = x++;
                }
                if (y == -1) {
                    y = K - 1;
                }
                if (x == K) {
                    x = 0;
                }
            }
        }
        allocate_tickets(a);
        return ans;
    }
    if (N <= 80 && M <= 80) {
        vector pre(N, vector<ll>(K + 1));
        vector suf(N, vector<ll>(K + 1));
        for (int i = 0; i < N; i++) {
            for (int j = 0; j < K; j++) {
                pre[i][j + 1] = pre[i][j] + x[i][j];
                suf[i][j + 1] = suf[i][j] + x[i][M - 1 - j];
            }
        }
        vector dp(N + 1, vector<ll>(N * K / 2 + 1, -1e18));
        dp[0][0] = 0;
        for (int i = 0; i < N; i++) {
            for (int j = 0; j <= K; j++) {
                for (int k = j; k <= N * K / 2; k++) {
                    dp[i + 1][k] = max(dp[i + 1][k], dp[i][k - j] + suf[i][j] - pre[i][K - j]);
                }
            }
        }
        vector a(N, vector<int>(M, -1));
        int s = 0, t = K - 1;
        for (int i = N - 1, j = N * K / 2; i >= 0; i--) {
            for (int k = 0; k <= min(j, K); k++) {
                if (dp[i][j - k] + suf[i][k] - pre[i][K - k] == dp[i + 1][j]) {
                    for (int p = 0; p < K - k; p++) {
                        a[i][p] = s++;
                        if (s == K) {
                            s = 0;
                        }
                    }
                    for (int p = K - 1; p >= K - k; p--) {
                        a[i][p] = t--;
                        if (t == -1) {
                            t = K - 1;
                        }
                    }
                    j -= k;
                    break;
                }
            }
        }
        allocate_tickets(a);
        return dp[N][N * K / 2];
    }
}

Compilation message (stderr)

tickets.cpp: In function 'll find_maximum(int, std::vector<std::vector<int> >)':
tickets.cpp:126:1: warning: control reaches end of non-void function [-Wreturn-type]
  126 | }
      | ^

• Subtask 1: 11 / 11
• Subtask 2: 16 / 16
• Subtask 3: 0 / 14
• Subtask 4: 14 / 14
• Subtask 5: 0 / 12
• Subtask 6: 0 / 23
• Subtask 7: 0 / 10