Submission #559040

#	Time	Username	Problem	Language	Result	Execution time	Memory
559040		Mamedov	기지국 (IOI20_stations)	C++17	0 / 100	3051 ms	2097152 KiB

stations

#include "stations.h"
#include <bits/stdc++.h>
#define pii pair<int, int>
#define f first
#define s second

using namespace std;

/*
  Label v with tin[v] for even levels and tout[v] for odd levels.
  This gives us labels of even numbers between [0, 2*n-2].
  We can divide each label by 2, so we get all labels in [0, n-1]

  Note: We can always restore [tin[v], tout[v]] by v and its neighbors' labels.
*/

vector<vector<int>>g;
vector<int>tin, tout;
vector<int>labels;
int timer = 0;

void dfs(int v, int par, int level) {
  tin[v] = timer++;
  for (int to : g[v]) {
    if (to != par) {
      dfs(to, v, level + 1);
    }
  }
  tout[v] = timer++;
  if (level % 2 == 0) {
    labels[v] = tin[v];
  } else {
    labels[v] = tout[v];
  }
}

int compress(int n, vector<int> &v) {
  vector<pii>p(n);
  for (int i = 0; i < n; ++i) {
    p[i].f = v[i];
    p[i].s = i;
  }
  sort(p.begin(), p.end());
  int new_val = 0;
  for (int i = 0; i < n - 1; ++i) {
    v[p[i].s] = new_val;
    if (p[i + 1].f != p[i].f) {
      ++new_val;
    }
  }
  v[p[n - 1].s] = new_val;
  return new_val;
}

vector<int> label(int n, int k, vector<int> u, vector<int> v) {
  g.resize(n);
  tin.resize(n);
  tout.resize(n);
  labels.resize(n);
  for (int i = 0; i < n - 1; ++i) {
    g[u[i]].emplace_back(v[i]);
    g[v[i]].emplace_back(u[i]);
  }
  dfs(0, 0, 0);
  compress(n, labels);
  return labels;
}

int find_next_station(int s, int t, vector<int> c) {
  if (c[0] > s) {  /// s is labeled with tin[]
    if (t < s) {
      return c.back();
    } else {
      auto itr = lower_bound(c.begin(), c.end(), t);
      if (itr == c.end()) --itr;
      return (*itr);
    }
  } else {  /// s is labeled with tout[]
    if (t > s) {
      return c[0];
    } else {
      auto itr = upper_bound(c.begin(), c.end(), t);
      if (itr != c.begin()) --itr;
      return (*itr);
    }
  }
}

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