Submission #463795

#	Time	Username	Problem	Language	Result	Execution time	Memory
463795		AlexLuchianov	007 (CEOI14_007)	C++14	100 / 100	316 ms	17696 KiB

007

#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <algorithm>

using ll = long long;

int const nmax = 200000;

std::vector<int> bfs(int n, int node, std::vector<std::vector<int>> &g) {
  std::vector<int> dist(n, -1);
  std::queue<int> q;
  q.push(node);
  dist[node] = 0;
  while(0 < q.size()) {
    node = q.front();
    q.pop();
    for(int h = 0; h < g[node].size(); h++) {
      int to = g[node][h];
      if(dist[to] == -1) {
        dist[to] = dist[node] + 1;
        q.push(to);
      }
    }
  }
  return dist;
}

int main() {
  std::ios::sync_with_stdio(0);
  std::cin.tie(0);

  int n, m;
  std::cin >> n >> m;
  int start1, start2, stop1, stop2;
  std::cin >> start1 >> start2 >> stop1 >> stop2;
  start1--;
  start2--;
  stop1--;
  stop2--;
  std::vector<std::vector<int>> g(n);
  for(int i = 1;i <= m; i++) {
    int x, y;
    std::cin >> x >> y;
    x--;
    y--;
    g[x].push_back(y);
    g[y].push_back(x);
  }
  std::vector<int> dist1(n), dist2(n);
  std::vector<int> trap1(n), trap2(n);
  dist1 = bfs(n, start1, g);
  dist2 = bfs(n, start2, g);
  trap1 = bfs(n, stop1, g);
  trap2 = bfs(n, stop2, g);
  
  int a = dist2[stop1] - dist1[stop1];
  int b = dist2[stop2] - dist1[stop2];

  if(a < 0 || b < 0)
    std::cout << -1 << '\n';
  else {
    int juke = 0, juke2 = 0;
    for(int i = 0; i < n; i++)
      if(dist1[i] + trap1[i] == dist1[stop1] && dist1[i] + trap2[i] == dist1[stop2])
        juke = std::max(juke, dist1[i]);
    for(int i = 0; i < n; i++)
      if(dist2[i] + trap1[i] == dist2[stop1] && dist2[i] + trap2[i] == dist2[stop2])
        juke2 = std::max(juke2, dist2[i]);
    if(a != b)
      std::cout << std::min(a, b) << '\n';
    else {
      if(juke + a < juke2)
        std::cout << a - 1 << '\n';
      else
        std::cout << a << '\n';
    }
  }
  return 0;
}

Compilation message (stderr)

007.cpp: In function 'std::vector<int> bfs(int, int, std::vector<std::vector<int> >&)':
007.cpp:19:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 |     for(int h = 0; h < g[node].size(); h++) {
      |                    ~~^~~~~~~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 70 / 70