Submission #612024

#	Time	Username	Problem	Language	Result	Execution time	Memory
612024		daria	Stations (IOI20_stations)	C++17	0 / 100	907 ms	796 KiB

stations

#include"bits/stdc++.h"
#include "stations.h"
#include <vector>
using namespace std;

const int N = 2000;

int T;
vector<int> adj[N], lb(N);
vector<bool> vis(N);

void dfs(int s, bool b){ //b = 0 apertura, b = 1 chiusura
 if(vis[s]) return;
 vis[s] = 1;
 if(!b) lb[s] = T; T++;
 for(int u : adj[s]) dfs(u, 1-b);
 if(b) lb[s] = T+N; T++;
}

vector<int> label(int n, int k, vector<int> u, vector<int> v) {
 for(int i=0; i<n; ++i) adj[i].clear();
 lb.resize(n);
 fill(lb.begin(), lb.end(), -1);
 fill(vis.begin(), vis.end(), 0);
 T = 0;

 for(int i=0; i<n-1; ++i){
  adj[u[i]].push_back(v[i]);
  adj[v[i]].push_back(u[i]);
 }
 dfs(0, 0);\
 //for(int i=0; i<n; ++i) cout << i << " " << lb[i] << endl;
 return lb;
}

int find_next_station(int s, int t, vector<int> c) {
 int par;
 if(s < N){ //s apertura
  // le altre sono tutte chiusure
  par = 0;
  for(int u : c) par = max(par, u);
  if(t < N){ //t apertura
   if(t <= s) return par;
   for(int i=0; i<c.size(); ++i) if(c[i] <= t+N) return c[i];
  } else{ // t chiusura
   if(t-N <= s) return par;
   for(int i=c.size()-1; i>=0; --i) if(c[i] >= t) return c[i];
  } return par;
 } else{ // s chiusura
  // le altre sono tutte aperture
  par = 40001;
  for(int u : c) par = min(par, u);
  if(t < N){ //t apertura
   if(t+N >= s) return par;
   for(int i=c.size()-1; i>=0; --i) if(c[i] <= t) return c[i];
  } else{ // t chiusura
   if(t+N <= s) return par;
   for(int i=0; i<c.size(); ++i) if(c[i]+N >= t) return c[i];
  } return par;
 }
}

/*
sai che t é stato visitato in un dato istante x; se tu sai che la tua é un’apertura e vale y:
se x < y allora devi salire a tuo padre
se x > y allora:
- o é un figlio —> per i figli controlli se la loro chiusura é avvenuta prima o dopo di x; se é vkavvenuta prima allora x é nel sottoalbero corrispondente
- altrimenti devi salire a tuo padre

per salire: il padre é quello con la chiusura più grande tra tutti i figli
*/

Compilation message (stderr)

stations.cpp: In function 'void dfs(int, bool)':
stations.cpp:15:2: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   15 |  if(!b) lb[s] = T; T++;
      |  ^~
stations.cpp:15:20: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   15 |  if(!b) lb[s] = T; T++;
      |                    ^
stations.cpp:17:2: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   17 |  if(b) lb[s] = T+N; T++;
      |  ^~
stations.cpp:17:21: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   17 |  if(b) lb[s] = T+N; T++;
      |                     ^
stations.cpp: In function 'int find_next_station(int, int, std::vector<int>)':
stations.cpp:44:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |    for(int i=0; i<c.size(); ++i) if(c[i] <= t+N) return c[i];
      |                 ~^~~~~~~~~
stations.cpp:58:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   58 |    for(int i=0; i<c.size(); ++i) if(c[i]+N >= t) return c[i];
      |                 ~^~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 8
• Subtask 3: 0 / 16
• Subtask 4: 0 / 10
• Subtask 5: 0 / 61