Submission #1092122

#	Time	Username	Problem	Language	Result	Execution time	Memory
1092122		0x34c	Bitaro’s Party (JOI18_bitaro)	C++17	0 / 100	2097 ms	8540 KiB

bitaro

#include <bits/stdc++.h>
#define ll long long
#define pii pair<int, int>
#define endl '\n'

using namespace std;

const int BLOCK_SZ = 300;
const int MAX_N = 1e5 + 1;
vector<int> graph[MAX_N];
bool mark[MAX_N];
vector<pii> paths[MAX_N];

int dfs(int v)
{
    int ret = mark[v] ? -1 : 0;

    for (int u : graph[v])
    {
        int res = dfs(u);
        if (res != -1)
            ret = max(ret, res + 1);
    }

    return ret;
}

void pre_comp(int v)
{
    vector<pii> cur;
    for (int u : graph[v])
        for (pii pth : paths[u])
            cur.push_back({pth.first + 1, pth.second});

    cur.push_back({0, v});
    sort(cur.begin(), cur.end(), greater<pii>());
    for (pii &p : cur)
    {
        if (!mark[p.second])
        {
            paths[v].push_back(p);
            mark[p.second] = true;
        }
    }

    for (pii &p : cur)
        mark[p.second] = false;

    while (paths[v].size() > BLOCK_SZ)
        paths[v].pop_back();
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int N, M, Q;
    cin >> N >> M >> Q;

    for (int i = 0; i < M; i++)
    {
        int a, b;
        cin >> a >> b;
        --a;
        --b;

        graph[b].push_back(a);
    }

    for (int v = 0; v < N; v++)
        pre_comp(v);

    while (Q--)
    {
        int t, y;
        cin >> t >> y;
        --t;

        vector<int> cs(y);
        for (int i = 0; i < y; i++)
        {
            cin >> cs[i];
            --cs[i];
            mark[cs[i]] = true;
        }

        if (y >= BLOCK_SZ)
            cout << dfs(t) << endl;
        else
        {
            bool ok = false;
            for (pii pth : paths[t])
            {
                if (!mark[pth.second])
                {
                    cout << pth.first << endl;
                    ok = true;
                    break;
                }
            }

            if (!ok)
                cout << -1 << endl;
        }

        for (int c : cs)
            mark[c] = false;
    }
}

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