Submission #387825

#	Time	Username	Problem	Language	Result	Execution time	Memory
387825		WLZ	Stations (IOI20_stations)	C++14	100 / 100	897 ms	852 KiB

stations

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

int dfs_cnt = 0;
vector< vector<int> > g;
vector<int> d, dfs_in, dfs_out;

void dfs(int u, int p) {
  dfs_in[u] = dfs_cnt++;
  for (auto& v : g[u]) {
    if (v != p) {
      d[v] = d[u] + 1;
      dfs(v, u);
    }
  }
  dfs_out[u] = dfs_cnt++;
}

vector<int> label(int n, int k, vector<int> u, vector<int> v) {
  g.assign(n, {});
  d.assign(n, 0);
  for (int i = 0; i < n - 1; i++) {
    g[u[i]].push_back(v[i]);
    g[v[i]].push_back(u[i]);
  }
  dfs_in.assign(n, 0); dfs_out.assign(n, 0);
  dfs(0, -1);
  set<int> st;
  for (int i = 0; i < n; i++) {
    if (d[i] % 2 == 0) st.insert(dfs_in[i]);
    else st.insert(dfs_out[i]);
  }
  int cur = 0;
  map<int, int> mp;
  for (auto& x : st) mp[x] = cur++;
  vector<int> ans(n);
  for (int i = 0; i < n; i++) {
    if (d[i] % 2 == 0) ans[i] = mp[dfs_in[i]];
    else ans[i] = mp[dfs_out[i]];
  }
  return ans;
}

int find_next_station(int s, int t, vector<int> c) {
  for (auto& x : c) if (x == t) return t;
  sort(c.begin(), c.end());
  if (s < c[0]) { // in
    for (int i = 0; i < (int) c.size() - 1; i++) if (s < t && t < c[i]) return c[i];
    return c.back();
  } else { // out
    for (int i = (int) c.size() - 1; i >= 1; i--) if (c[i] < t && t < s) return c[i];
    return c[0];
  }
}

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