Submission #786673

#	Time	Username	Problem	Language	Result	Execution time	Memory
786673		PanosPask	Bitaro’s Party (JOI18_bitaro)	C++14	7 / 100	2058 ms	438988 KiB

bitaro

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

using namespace std;

typedef pair<int, int> pi;

int N, M, Q;
vector<map<int, int>> temp_dist;
vector<vector<pi>> dist;
vector<vector<int>> adj_list;
int BLOCK_SIZE;
vector<bool> ban;
vector<int> curbanned;
vector<int> dp;

int find(int i, vector<int>& v)
{
    int p = lower_bound(v.begin(), v.end(), i) - v.begin();

    if (p < v.size() && v[p] == i)
        return true;
    else
        return false;
}

int naive_dp(int dest, vector<bool>& banned)
{
    dp.assign(N, -1);

    for (int i = 0; i < N; i++) {
        if (!banned[i]) {
            dp[i] = max(dp[i], 0);
        }
        if (dp[i] == -1) {
            continue;
        }

        for (auto v : adj_list[i])
            dp[v] = max(dp[v], dp[i] + 1);
    }

    return dp[dest];
}

int find_from_precalculate(int c, vector<bool>& banned)
{
    int ans = -1;
    for (auto v : dist[c]) {

        if (!banned[v.first])
            ans = max(ans, v.second);
    }

    return ans;
}

bool insert_to(int dest, int src, int len)
{
    if (temp_dist[dest].find(src) != temp_dist[dest].end()) {
        temp_dist[dest][src] = max(temp_dist[dest][src], len);
        return true;
    }

    if (temp_dist[dest].size() < BLOCK_SIZE) {
        temp_dist[dest][src] = len;
        return true;
    }
    else {
        auto v = *temp_dist[dest].begin();
        if (v.second < len) {
            temp_dist[dest].erase(v.first);
            temp_dist[dest][src] = len;
            return true;
        }
        return false;
    }
}

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

    BLOCK_SIZE = ceil(sqrt(N));

    adj_list.resize(N);
    dist.resize(N);
    temp_dist.resize(N);
    ban.resize(N);

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

        adj_list[u].pb(v);
    }

    // Precalculate best cities
    for (int i = 0; i < N; i++) {
        insert_to(i, i, 0);

        for (auto v : temp_dist[i])
            dist[i].push_back(v);
        temp_dist[i].clear();

        sort(dist[i].begin(), dist[i].end(), [](pi& a, pi& b) {return a.second > b.second;});

        for (auto neigh : adj_list[i]) {
            for (auto city : dist[i]) {
                if (!insert_to(neigh, city.first, city.second + 1))
                    break;
            }
        }
    }

    temp_dist.clear();

    for (int i = 0; i < Q; i++) {
        int T, Y;
        scanf("%d %d", &T, &Y);
        T--;

        for (int j = 0; j < Y; j++) {
            int c;
            scanf("%d", &c);
            c--;

            curbanned.push_back(c);
            ban[c] = true;
        }
        sort(curbanned.begin(), curbanned.end());

        int ans = 0;
        if (Y >= BLOCK_SIZE)
            ans = naive_dp(T, ban);
        else
            ans = find_from_precalculate(T, ban);

        while (curbanned.size()) {
            ban[curbanned.back()] = false;
            curbanned.pop_back();
        }

        printf("%d\n", ans);
    }

    return 0;
}

Compilation message (stderr)

bitaro.cpp: In function 'int find(int, std::vector<int>&)':
bitaro.cpp:21:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |     if (p < v.size() && v[p] == i)
      |         ~~^~~~~~~~~~
bitaro.cpp: In function 'bool insert_to(int, int, int)':
bitaro.cpp:65:32: warning: comparison of integer expressions of different signedness: 'std::map<int, int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   65 |     if (temp_dist[dest].size() < BLOCK_SIZE) {
      |         ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
bitaro.cpp: In function 'int main()':
bitaro.cpp:82:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   82 |     scanf("%d %d %d", &N, &M, &Q);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
bitaro.cpp:93:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   93 |         scanf("%d %d", &u, &v);
      |         ~~~~~^~~~~~~~~~~~~~~~~
bitaro.cpp:121:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  121 |         scanf("%d %d", &T, &Y);
      |         ~~~~~^~~~~~~~~~~~~~~~~
bitaro.cpp:126:18: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  126 |             scanf("%d", &c);
      |             ~~~~~^~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 0 / 7
• Subtask 3: 0 / 86