Submission #297445

#	Time	Username	Problem	Language	Result	Execution time	Memory
297445		Haunted_Cpp	Dreaming (IOI13_dreaming)	C++17	0 / 100	129 ms	19980 KiB

dreaming

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

const int MAX_N = 1e5 + 5;

vector<vector<pair<int, int>>> g(MAX_N);
vector<vector<pair<int, int>>> tree(MAX_N);
vector<int> par(MAX_N);

bitset<MAX_N> vis;

pair<int, int> best_way = {-1, -1};
void find_diam(const vector<vector<pair<int, int>>>& graph, int node, int p, int w) {
  par[node] = p;
  vis[node] = 1;
  best_way = max(best_way, {w, node});
  for (auto [to, cost] : graph[node]) {
    if (to != p) {
      find_diam(graph, to, node, w + cost);
    }
  }
}

int big(const vector<vector<pair<int, int>>>& graph, int node, int p, int w) {
  int mx = w;
  for (auto [to, cost] : graph[node]) {
    if (to != p) {
      mx = max(mx, big(graph, to, node, w + cost));
    }
  }
  return mx;
}

pair<int, int> find_center(const vector<vector<pair<int, int>>>& graph, int node) {
  best_way = {-1, -1};
  find_diam(graph, node, -1, 0);
  int L = best_way.second;
  best_way = {-1, -1};
  find_diam(graph, L, -1, 0);
  int R = best_way.second;
  int longest_path = best_way.first;
  vector<int> path;
  while(R != L) {
    path.emplace_back(R);
    R = par[R];
  }
  path.emplace_back(R);
  const int mid = (int) path.size() / 2;
  if ( (int) path.size() & 1) {
    return {path[mid], longest_path};
  }
  auto A = make_pair(big(graph, path[mid], -1, 0), path[mid]);
  auto B = make_pair(big(graph, path[mid - 1], -1, 0), path[mid - 1]);
  return { (A.first < B.first ? A.second : B.second), longest_path};
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
  for (int i = 0; i < M; i++) {
    g[A[i]].emplace_back(B[i], T[i]);
    g[B[i]].emplace_back(A[i], T[i]);
    tree[A[i]].emplace_back(B[i], T[i]);
    tree[B[i]].emplace_back(A[i], T[i]);
  }
  int nxt = -1;
  for (int i = 0; i < N; i++) {
    if (!vis[i]) {
      auto w = find_center(g, i);
      if (nxt != -1) {
        tree[nxt].emplace_back(w.first, L);
        tree[w.first].emplace_back(nxt, L);
      }
      nxt = w.first;
    }
  }
  return find_center(tree, 0).second;
}

• Subtask 1: 0 / 14
• Subtask 2: 0 / 10
• Subtask 3: 0 / 23
• Subtask 4: 0 / 18
• Subtask 5: 0 / 12
• Subtask 6: 0 / 23