Submission #486474

#	Time	Username	Problem	Language	Result	Execution time	Memory
486474		fun_day	Jakarta Skyscrapers (APIO15_skyscraper)	C++14	0 / 100	1 ms	204 KiB

skyscraper

#include <bits/stdc++.h>

using namespace std;

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int n , m;
  cin >> n >> m;
  vector<pair<int,int>> cost(n , {0 , 0});
  vector<int> id(m);
  vector<bool> have(n);
  for(int i = 0 ; i < m ; i++){
    int a , b;
    cin >> a >> b;
    have[a] = true;
    cost[a] = make_pair(b , i);
    id[i] = b;
  }
  if(!have[0] || n == 1){
    cout << -1 << '\n';
    return 0;
  }
  // assert that 0 has a cost
  vector<vector<int>> dist(n , vector<int>(m , (int)1e9));
  vector<vector<bool>> vis(n , vector<bool>(m));
  vis[0][cost[0].second] = true;
  priority_queue<pair<int,pair<int,int>> , vector<pair<int,pair<int,int>>> , greater<pair<int,pair<int,int>>>> pq;
  dist[0][cost[0].second] = 0;
  auto is_right = [&](int node , int idx){
    return node >= 0 && node < n && !vis[node][idx];
  };
  pq.emplace(0 , make_pair(0 , cost[0].second));
  while(!pq.empty()){
    auto f = pq.top();
    pq.pop();
    if(f.first != dist[f.second.first][f.second.second]) continue;
    for(int i = 0 ; i < 2 ; i++){
      int cur = (i ? 1 : -1);
      int who = f.second.first + cur * id[f.second.second];
      if(!is_right(who , f.second.second)) continue;
      if(dist[who][f.second.second] > f.first + 1){
        dist[who][f.second.second] = f.first + 1;
        pq.emplace(dist[who][f.second.second] , make_pair(who , f.second.second));
        if(!vis[who][cost[who].second] && cost[who].second != 0) {
          dist[who][cost[who].second] = dist[who][f.second.second];
          pq.emplace(dist[who][f.second.second] , make_pair(who , cost[who].second));
          vis[who][cost[who].second] = true;
        }
        vis[who][f.second.second] = true;
      }
    }
  }
  int best = (int)1e9;
  for(int i = 0 ; i < m ; i++){
    best = min(best , dist[1][i]);
  }
  if(best == (int)1e9){
    cout << -1 << '\n';
  }
  else cout << best << '\n';
  return 0; 
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 12
• Subtask 3: 0 / 14
• Subtask 4: 0 / 21
• Subtask 5: 0 / 43