Submission #1173075

#	Time	Username	Problem	Language	Result	Execution time	Memory
1173075		dombly	Event Hopping (BOI22_events)	C++20	10 / 100	1597 ms	43668 KiB

events

#include <bits/stdc++.h>
#define F first
#define S second

using namespace std;

const int N = 5000 + 10;

int Dist[N][N], n, l[N], r[N];
vector<int> g[N];

void Bfs(int s) {
  for(int i = 1; i <= n; i++) Dist[s][i] = n + 1;
  queue<int> q;
  Dist[s][s] = 0;
  q.push(s);
  while(!q.empty()) {
    int u = q.front();
    q.pop();
    for(int j : g[u]) {
      if(Dist[s][j] > Dist[s][u] + 1) {
        Dist[s][j] = Dist[s][u] + 1;
        q.push(j);
      }
    }
  }
}

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

  int q;
  cin >> n >> q;
  for(int i = 1; i <= n; i++) cin >> l[i] >> r[i];
  for(int i = 1; i <= n; i++) {
    for(int j = 1; j <= n; j++) {
      if(i != j && l[j] <= r[i] && r[j] >= r[i]) {
        //cout << i << " -> " << j << endl;
        g[i].push_back(j);
      }
    }
  }
  for(int i = 1; i <= n; i++) Bfs(i);
  while(q--) {
    int l, r;
    cin >> l >> r;
    if(Dist[l][r] == n + 1) {
      cout << "impossible\n";
    } else {
      cout << Dist[l][r] << "\n";
    }
  }
}

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