Submission #421780

#	Time	Username	Problem	Language	Result	Execution time	Memory
421780		Sundavar	Highway Tolls (IOI18_highway)	C++14	0 / 100	16 ms	1268 KiB

highway

#include <bits/stdc++.h>
#include "highway.h"
using namespace std;
typedef pair<int,int> pii;
typedef long long ll;
struct node{
  vector<pii> to;
  int depth = 0, start = -1, with = -1;
};
vector<node> graph;

int getEdge(int l, int r, int M, ll dist){
  if(l+1 == r) return l;
  vector<int> s(M, 0);
  int m = (l+r)/2;
  for(int i = l; i < m; i++) s[i] = 1;
  ll x = ask(s);
  //cout<<l<<" "<<r<<" "<<x<<endl;
  if(x == dist)
    return getEdge(m, r, M, dist);
  else
    return getEdge(l, m, M, dist);
}
void BFS(int x, int y){
  queue<int> q;
  q.push(x), q.push(y);
  graph[x].start = x, graph[y].start = y;
  while(q.size() > 0){
    int curr = q.front();
    q.pop();
    for(pii& a : graph[curr].to)
      if(graph[a.first].start == -1){
        q.push(a.first);
        graph[a.first].start = graph[curr].start;
        graph[a.first].depth = graph[curr].depth + 1;
        graph[a.first].with = a.second;
      }
  }
}
int find(int u, int N, int M, ll lenght, ll A, ll B){
  vector<int> S(M, 0);
  for(int i = 0; i < N; i++)
    if(graph[i].start == u && graph[i].with != -1) S[graph[i].with] = 1;
  int dist = (ask(S)-lenght*A)/(B-A);
  vector<int> poss;
  for(int i = 0; i < N; i++)
    if(graph[i].start == u && graph[i].depth == dist) 
      poss.push_back(i);

  while(poss.size() > 1){
    S.assign(M, 0);
    for(int i = 0; i < poss.size()/2; i++) S[graph[poss[i]].with] = 1;
    if(ask(S) == lenght*A){
      vector<int> uj;
      for(int i = poss.size()/2; i < poss.size(); i++) uj.push_back(poss[i]);
      poss = uj;
    }
    else poss.resize(poss.size()/2);
  }
  return poss[0];
}
void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
  graph.resize(N);
  int M = U.size();
  for(int i = 0; i < M; i++){
    graph[U[i]].to.push_back({V[i],i});
    graph[V[i]].to.push_back({U[i],i});
  }
  vector<int> S(M, 0);
  ll dist = ask(S), length = dist/A;
  cout<<dist<<endl;
  int ind = getEdge(0, M, M, dist);
  cout<<ind<<endl;
  BFS(U[ind], V[ind]);
  answer(find(U[ind], N, M, length, A, B), find(V[ind], N, M, length, A, B));
}

Compilation message (stderr)

highway.cpp: In function 'int find(int, int, int, ll, ll, ll)':
highway.cpp:52:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   52 |     for(int i = 0; i < poss.size()/2; i++) S[graph[poss[i]].with] = 1;
      |                    ~~^~~~~~~~~~~~~~~
highway.cpp:55:36: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   55 |       for(int i = poss.size()/2; i < poss.size(); i++) uj.push_back(poss[i]);
      |                                  ~~^~~~~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 7
• Subtask 3: 0 / 6
• Subtask 4: 0 / 33
• Subtask 5: 0 / 18
• Subtask 6: 0 / 31