Submission #1109033

#	Time	Username	Problem	Language	Result	Execution time	Memory
1109033		n3rm1n	Event Hopping (BOI22_events)	C++17	0 / 100	3 ms	1104 KiB

events

#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
const int MAXN = 5e3 + 10;
void speed()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
}
int n, q, s[MAXN], e[MAXN];
void read_events()
{
    cin >> n >> q;
    for (int i = 1; i <= n; ++ i)
        cin >> s[i] >> e[i];
}
vector < int > g[MAXN];

void make_edges()
{
    for (int i = 1; i <= n; ++ i)
    {
        for (int j = 1; j <= n; ++ j)
        {
            if(i == j)continue;
            if(s[j] <= e[i] && e[i] <= e[j])
                g[i].push_back(j);
        }
    }
}
vector < pair < int, int > > que[MAXN];
int ans[MAXN];
int start, dist[MAXN], used[MAXN];
void bfs()
{
    for (int i = 1; i <= n; ++ i)
    {
        dist[i] = 1e9;
    }
    queue < int > q;
    q.push(start);
    used[start] = 1;
    dist[start] = 0;
    while(!q.empty())
    {
        int beg = q.front();
        q.pop();
        for (auto nb: g[beg])
        {
            if(used[nb])continue;
            dist[nb] = dist[beg] + 1;
            used[nb] = 1;
            q.push(nb);
        }
    }
}
void sort_queries()
{
    for (int i = 1; i <= q; ++ i)
    {
        int from, to;
        cin >> from >> to;
        que[from].push_back(make_pair(to, i));
    }
}
int main()
{
    speed();

    read_events();
    make_edges();
    sort_queries();
    for (int i = 1; i <= n; ++ i)
    {
        if(!que[i].size())continue;
        start = i;
        bfs();
        for (auto &[v, qi]: que[i])
        {
            ans[qi] = dist[v];
        }
    }
    for (int i = 1; i <= q; ++ i)
    {
        assert(ans[i] <= 1e9);
        assert(ans[i] >= 0);
        if(ans[i] == 1e9)cout << "impossible" << endl;
        else cout << ans[i] << endl;
    }
    return 0;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 30