Submission #864142

#	Time	Username	Problem	Language	Result	Execution time	Memory
864142		danikoynov	Event Hopping (BOI22_events)	C++14	10 / 100	1566 ms	48328 KiB

events

#include<bits/stdc++.h>
#define debug true
#ifdef DEVAL 
    #define debug false
#endif

using namespace std;

const int maxn = 1e5 + 10;

struct interval
{
    int s, e;
}seg[maxn];

int n, q;   
pair < int, int > task[maxn];
void read()
{
    cin >> n >> q;
    for (int i = 1; i <= n; i ++)
    {
        cin >> seg[i].s >> seg[i].e;
    }
    for (int i = 1; i <= q; i ++)
    {
        cin >> task[i].first >> task[i].second;
    }
}


vector < int > adj[maxn];

int used[maxn], dist[5010][5010];

void bfs(int start)
{
    for (int i = 1; i <= n; i ++)
        used[i] = -1;

    used[start] = 0;
    queue < int > q;
    q.push(start);
    while(!q.empty())
    {
        int v = q.front();
        q.pop();
        for (int u : adj[v])
        {
            if (used[u] == - 1)
            {
                used[u] = used[v] + 1;
                q.push(u);
            }
        }
    }
}

void build_graph()
{
    for (int i = 1; i <= n; i ++)
       for (int j = 1; j <= n; j ++)
        {
            if (seg[j].s <= seg[i].e && seg[i].e <= seg[j].e)
                adj[i].push_back(j);
        }
}

void answer_queries()
{
    for (int i = 1; i <= q; i ++)
    {
        if (dist[task[i].first][task[i].second] == -1)
            cout << "impossible" << endl;
        else
            cout << dist[task[i].first][task[i].second] << endl;

    }
}

void precalc()
{
    for (int v = 1; v <= n; v ++)
    {
        bfs(v);
        for (int i = 1; i <= n; i ++)
            dist[v][i] = used[i];
    }
}
void solve()
{
    read();
    build_graph();
    precalc();
    answer_queries();    
}

int main()
{
    solve();
    return 0;
}

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