Submission #757754

#	Time	Username	Problem	Language	Result	Execution time	Memory
757754		taher	Dreaming (IOI13_dreaming)	C++17	59 / 100	1065 ms	11288 KiB

dreaming

#include <bits/stdc++.h>
#include "dreaming.h"

using namespace std;

const int maxN = (int) 1e5 + 1;
vector<vector<pair<int,int>>> adj;
int cnt = 0, n, m, l,sz = 0, ans = 0;
bool vis[maxN];
int parent[maxN];
vector<pair<int,int>> p;

void init(){
  adj.resize(n);
  p.resize(n);
  memset(parent, -1, sizeof(parent));
}

pair<int, int> bfs(int node){
  sz = 0;
  bool seen[n];
  int depth[n];
  memset(seen, 0, sizeof(seen));
  memset(depth, 0, sizeof(depth));
  int best_node = node, best_dist = 0;
  depth[node] = 0;
  seen[node] = true; vis[node] = true;
  queue<int> qs;
  qs.emplace(node);
  while(!qs.empty()){
    auto f = qs.front();
    sz++;
    if(depth[f] > best_dist){
      best_dist = depth[f];
      best_node = f;
    }
    qs.pop();
    for(auto x : adj[f]){
      if(seen[x.first]) continue;
      vis[x.first] = true;
      qs.emplace(x.first);
      parent[x.first] = f;
      depth[x.first] = x.second + depth[f];
      seen[x.first] = true;
    }
  }
  return make_pair(best_node, best_dist);
}

int Get_total(int node){
  auto val = bfs(node);
  auto f = bfs(val.first);
  return f.second;
}

void Do(int node){
  auto val = bfs(node);
  if(sz == 1) {
    p[cnt++] = make_pair(0, node);
    return ;
  }
  auto Tke = bfs(val.first);
  parent[val.first] = -1;
  int cur = Tke.first;
  vector<int> path, len;
  while(cur != -1){
    int nxt = parent[cur];
    path.emplace_back(cur);
    if(nxt == -1) break;
    auto q = lower_bound(adj[cur].begin(),adj[cur].end(), make_pair(nxt, 0));
    len.emplace_back((*q).second);
    cur = parent[cur];    
  }
  int Max = (int)1e9, best_node = -1, s = 0;
  for(int i = 0; i < (int)path.size(); i++){
    if(i > 0) s += len[i - 1];
    int now_max = max(s, Tke.second - s);
    if(now_max < Max){
      Max = now_max;
      best_node = path[i];
    }
  }
  ans = max(ans, Tke.second);
  assert(best_node != -1);
  p[cnt++] = make_pair(Max, best_node);
  return ;
}

void make(){
  for(int i = 0; i < n; i++){
    if(vis[i]) continue;
    Do(i);
    vis[i] = true;
  }
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
  n = N;
  m = M;
  l = L;
  init();

  for (int i = 0; i < m; i++) {
    adj[A[i]].emplace_back(B[i], T[i]);
    adj[B[i]].emplace_back(A[i], T[i]);
  }

  for(int i = 0; i < n; i++){
    sort(adj[i].begin(),adj[i].end());
  }

  make();

  sort(p.rbegin(), p.rend());
  if(cnt >= 2) {
    ans = max(ans, p[0].first + p[1].first + l);
  }
  if(cnt >= 3) {
    ans = max(ans, p[1].first + p[2].first + 2 * l);
  }
  return ans;
}

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