Submission #1318585

#	Time	Username	Problem	Language	Result	Execution time	Memory
1318585		Johan	Dreaming (IOI13_dreaming)	C++20	65 / 100	778 ms	35800 KiB

dreaming

#include "dreaming.h"
#include "bits/stdc++.h"
using namespace std;
const int N = 1e5 + 5;
int pa[N];
vector < int > adj[N];
unordered_map < int , int > dist, vis;
map < pair < int , int > , int > we;
vector < int > par(N, -1);
int find(int u){
  if(par[u] < 0)return u;
  else return par[u] = find(par[u]);
}
void uni(int u, int v){
  u = find(u);
  v = find(v);
  if(u == v)return;
  par[u] += par[v];
  par[v] = u;
}
int bfs(int st){
  queue < int > q;
  map < int , int > dis;
  q.push(st);
  dis[st] = 0;
  while(q.size() > 0){
    int u = q.front();
    q.pop();
    for(auto v : adj[u]){
      if(dis.count(v) == 0){
        dis[v] = dis[u] + we[{u, v}];
        q.push(v);
      }
    }
  }
  int node, mx = -1;
  for(auto [nd, val] : dis){
    if(val > mx){
      mx = val;
      node = nd;
    }
  }
  return node;
}
void dfs(int u, int end){
  vis[u] = true;
  for(auto v : adj[u]){
    if(!vis[v]){
      pa[v] = u;
      dfs(v, end);
    }
  }
}
pair < int , int > centre(int st, int end){
  int sz = 0;
  vector < int > path = {end};
  while(end != st){
    sz += we[{end, pa[end]}];
    end = pa[end];
    path.push_back(end);    
  }
  int mn = sz, diametr = sz, cur = 0, node = path[0], far;
  for(int i = 1; i < path.size(); i++){
    int W = we[{path[i], path[i - 1]}];
    sz -= W;
    cur += W;
    if(mn > max(sz, cur)){
      if(sz > cur)far = path.back();
      else far = path[0];
      mn = max(sz, cur);
      node = path[i];
    }
  }
  return {diametr, node};
}
pair < int , int > find_diametr(int Node){
	int u = bfs(Node);
  int v = bfs(u);
  dfs(u, v);
  return {u, v};
}
int travelTime(int n, int m, int L, int u[], int v[], int w[]){
  for(int i = 0; i < m; i++){
    we[{u[i], v[i]}] = w[i];
    we[{v[i], u[i]}] = w[i];
    adj[u[i]].push_back(v[i]);
    adj[v[i]].push_back(u[i]);  
    uni(u[i], v[i]);
  }
  set < int > cmps;
  for(int i = 0; i < n; i++)
    cmps.insert(find(i));
  vector < pair < int , int > > x;
  for(auto nd : cmps){
    pair < int , int > p = find_diametr(nd);
    int u = p.first;
    int v = p.second;
    x.push_back(centre(u, v));
  }
  sort(x.rbegin(), x.rend());
  int Node = x[0].second;
  for(int i = x.size() - 1; i >= 1; i--){
    adj[Node].push_back(x[i].second);
    adj[x[i].second].push_back(Node);
    we[{Node, x[i].second}] = L;
    we[{x[i].second, Node}] = L;
  }
  vis.clear();
  pair < int , int > p = find_diametr(Node);
  return centre(p.first, p.second).first;
}

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