Submission #306064

#	Time	Username	Problem	Language	Result	Execution time	Memory
306064		eriksuenderhauf	Stations (IOI20_stations)	C++17	10 / 100	966 ms	752 KiB

stations

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

vector<int> label(int n, int k, vector<int> u, vector<int> v) {
  vector<int> deg(n);
  vector<vector<int>> adj(n);
  for (int i = 0; i < n - 1; i++)
    deg[u[i]]++, deg[v[i]]++, adj[u[i]].push_back(v[i]), adj[v[i]].push_back(u[i]);;
  vector<int> labels(n);
  // if (*max_element(deg.begin(), deg.end()) <= 2) {
  //   int r = min_element(deg.begin(), deg.end()) - deg.begin(), p = -1;
  //   labels[r] = 0;
  //   for (int i = 1; i < n; i++) {
  //     if (~p) adj[r].erase(find(adj[r].begin(), adj[r].end(), p));
  //     tie(r, p) = make_pair(adj[r][0], r);
  //     labels[r] = i;
  //   }

  // iota(labels.begin(), labels.end(), 0);

  // function<void(int,int,int)> dfs = [&](int u, int p, int l) {
  //   labels[u] = l;
  //   adj[u].erase(find(adj[u].begin(), adj[u].end(), p));
  //   if (!adj[u].empty())
  //     dfs(adj[u][0], u, l+1);
  // };
  // int r = max_element(deg.begin(), deg.end()) - deg.begin();
  // int lo = 1; labels[r] = 0;
  // for (int v: adj[r]) {
  //   dfs(v, r, lo);
  //   lo += 1000;
  // }

  function<void(int,int)> init = [&](int u, int p) {
    if (~p) adj[u].erase(find(adj[u].begin(), adj[u].end(), p));
    for (int v: adj[u])
      init(v, u);
  };
  init(0, -1);
  function<void(int,int&)> dfs = [&](int u, int& l) {
    l |= 1 << u;
    for (int v: adj[u])
      dfs(v, l);
  };
  for (int i = 0; i < n; i++) {
    dfs(i, labels[i]);
    labels[i] |= i << 8;
  }
  return labels;
}

int find_next_station(int s, int t, vector<int> c) {
  vector<int> cand;
  int y = t >> 8, x = s >> 8;
  for (int i: c)
    if ((i >> y) & 1)
      cand.push_back(i);
  if (cand.size() == 1) return cand[0];
  if (cand.size() == 2) {
    int lo = cand[0] >> 8, hi = cand[1] >> 8;
    if ((cand[0] >> hi) & 1)
      return cand[1];
    return cand[0];
  }
  for (int i: c)
    if ((i >> x) & 1)
      return i;
  assert(0);

  // sort(c.begin(), c.end());
  // if (t == 0)
  //   return c[0];
  // if (s == 0)
  //   return ((t-1) / 1000) * 1000 + 1;
  // if ((s-1) / 1000 == (t-1) / 1000)
  //   return s < t ? c.back() : c[0];
  // return c[0];

  // set<int> tmp; for (int x: c) tmp.insert(x+1);
  // int y = t+1;
  // if (tmp.count(y)) return y-1;
  // while (y > 0) {
  //   y /= 2;
  //   if (tmp.count(y))
  //     return y-1;
  // }
  // return *min_element(c.begin(), c.end());

  // return s < t ? *max_element(c.begin(), c.end()) : *min_element(c.begin(), c.end());
}

Compilation message (stderr)

stations.cpp: In function 'int find_next_station(int, int, std::vector<int>)':
stations.cpp:61:9: warning: unused variable 'lo' [-Wunused-variable]
   61 |     int lo = cand[0] >> 8, hi = cand[1] >> 8;
      |         ^~

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