Submission #982536

#	Time	Username	Problem	Language	Result	Execution time	Memory
982536		PanosPask	Sailing Race (CEOI12_race)	C++14	40 / 100	3065 ms	14516 KiB

race

#include <bits/stdc++.h>
#define pb push_back

using namespace std;

int N, K;
vector<vector<int>> adj_list;

// dp[l][r][k]:  Maximum number of stages if enclosed by l, r
// and being in the stages such that l < s < r'
// Where r' = l > r ? r = r + N : r

// k == 0: Starting in l
// k == 1: Starting in r
vector<vector<vector<int>>> dp;

// True if a stage can be organized from i to j
bool stage(int i, int j)
{
    int pos = lower_bound(adj_list[i].begin(), adj_list[i].end(), j) - adj_list[i].begin();
    if (pos < adj_list[i].size() && adj_list[i][pos] == j) {
        return true;
    }

    return false;
}

int main(void)
{
    scanf("%d %d", &N, &K);

    adj_list.resize(N);
    dp.assign(N, vector<vector<int>>(N, vector<int>(2, 0)));

    for (int i = 0; i < N; i++) {
        int v;
        scanf("%d", &v);

        while (v != 0) {
            v--;
            adj_list[i].pb(v);
            scanf("%d", &v);
        }

        sort(adj_list[i].begin(), adj_list[i].end());
    }

    int ans = 0;
    int starting = 0;

    for (int len = 1; len <= N; len++) {
        for (int l = 0; l < N; l++) {
            int r_actual = l + len - 1;
            int r = r_actual % N;

            for (int i_actual = l + 1; i_actual < r_actual; i_actual++) {
                int i = i_actual % N;

                dp[l][r][0] = max(dp[l][r][0], dp[l][i][0]);
                dp[l][r][1] = max(dp[l][r][1], dp[i][r][1]);

                if (stage(l, i)) {
                    dp[l][r][0] = max(dp[l][r][0], 1 + dp[i][r][0]);
                }
                if (stage(r, i)) {
                    dp[l][r][1] = max(dp[l][r][1], 1 + dp[l][i][1]);
                }
            }

            if (stage(l, r)) {
                dp[l][r][0] = max(dp[l][r][0], 1 + dp[(l + 1) % N][r][1]);
            }
            if (stage(r, l)) {
                dp[l][r][1] = max(dp[l][r][1], 1 + dp[l][(r_actual - 1) % N][0]);
            }

            if (dp[l][r][0] > ans) {
                ans = dp[l][r][0];
                starting = l;
            }
            if (dp[l][r][1] > ans) {
                ans = dp[l][r][1];
                starting = r;
            }
        }
    }

    printf("%d\n%d\n", ans, starting + 1);

    return 0;
}

Compilation message (stderr)

race.cpp: In function 'bool stage(int, int)':
race.cpp:21:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |     if (pos < adj_list[i].size() && adj_list[i][pos] == j) {
      |         ~~~~^~~~~~~~~~~~~~~~~~~~
race.cpp: In function 'int main()':
race.cpp:30:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |     scanf("%d %d", &N, &K);
      |     ~~~~~^~~~~~~~~~~~~~~~~
race.cpp:37:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |         scanf("%d", &v);
      |         ~~~~~^~~~~~~~~~
race.cpp:42:18: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   42 |             scanf("%d", &v);
      |             ~~~~~^~~~~~~~~~

• Subtask 1: 40 / 100