Submission #329784

#	Time	Username	Problem	Language	Result	Execution time	Memory
329784		chenwz	Stations (IOI20_stations)	C++14	100 / 100	1172 ms	1240 KiB

stations

#include "stations.h"
#include <vector>
using namespace std;
typedef vector<int> IVec;

void rec(int u, int fa, bool dfs_in, int &clock, const vector<IVec>& G, IVec& L) {
  if (dfs_in) L[u] = clock++;
  for (int i : G[u])
    if (i != fa) rec(i, u, !dfs_in, clock, G, L);
  if (!dfs_in) L[u] = clock++;
}

IVec label(int n, int k, IVec u, IVec v) {
  IVec L(n);
  vector<IVec> G(n, IVec());
  for (int i = 0; i < u.size(); i++)
    G[u[i]].push_back(v[i]), G[v[i]].push_back(u[i]);
  int clock = 0;
  rec(0, -1, true, clock, G, L);
  return L;
}

int find_next_station(int s, int t, IVec c) {
  if (c[0] > s) { // Case 1: s is in InClock. All the neighbors' label > s.
    if (t < s || t > c.back()) return c.back(); // t not in this subtree, go to parent.
    int v = 0; // t is in this subtree, Pick the smallest ch >= t
    return *lower_bound(c.begin(), c.end(), t);
  }
  if (t < c[0]) // Case 2: node s is in the post_order level.
    return c[0]; // t not in subtree
  if (t > s) return c[0]; // t not in this subtree, go to the root.
  int v = c.size() - 1;
  while (c[v] > t) v--;
  return c[v];
}

Compilation message (stderr)

stations.cpp: In function 'IVec label(int, int, IVec, IVec)':
stations.cpp:16:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   16 |   for (int i = 0; i < u.size(); i++)
      |                   ~~^~~~~~~~~~
stations.cpp: In function 'int find_next_station(int, int, IVec)':
stations.cpp:26:9: warning: unused variable 'v' [-Wunused-variable]
   26 |     int v = 0; // t is in this subtree, Pick the smallest ch >= t
      |         ^

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