Submission #1318301

#	Time	Username	Problem	Language	Result	Execution time	Memory
1318301		Johan	Dreaming (IOI13_dreaming)	C++20	65 / 100	574 ms	36004 KiB

dreaming

#include "dreaming.h"
#include "bits/stdc++.h"
using namespace std;
const int N = 1e5 + 5;
int pa[N];
vector < int > adj[N];
map < int , int > dist;
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;
}
void dfs(int u, int p = -1){
  for(auto v : adj[u]){
    if(v != p){
      dist[v] = dist[u] + we[{u, v}];
      dfs(v, u);
    }
  }
}
void dfs_(int u, int end, int p = -1){
  pa[u] = p;
  for(auto v : adj[u]){
    if(v != p)
      dfs_(v, end, u);
  }
}
array < int , 3 > 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, mn};
}
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 < array < int , 3 > > x;
  for(auto nd : cmps){
    dfs(nd);
    int mx = 0, u = nd, v = nd;
    for(auto e : dist){
      int node = e.first;
      int dis = e.second;
      if(dis > mx){
        mx = dis;
        u = node;
      }
    }
    mx = 0;
    dist.clear();
    dfs(u);
    for(auto e : dist){
      int node = e.first;
      int dis = e.second;
      if(dis > mx){
        mx = dis;
        v = node;
      }
    }
    dist.clear();
    dfs_(u, v);
    x.push_back(centre(u, v));
  }
  sort(x.rbegin(), x.rend());
  int Node = x[0][1], diss = x[0][2];
  for(int i = 1; i < x.size(); i++){
    adj[Node].push_back(x[i][1]);
    adj[x[i][1]].push_back(Node);
    we[{Node, x[i][1]}] = L;
    we[{x[i][1], Node}] = L;
  }
  dfs(Node);
  int mx = 0, U = Node, V = Node;
  for(auto e : dist){
    int node = e.first;
    int dis = e.second;
    if(dis > mx){
      mx = dis;
      U = node;
    }
  }
  mx = 0;
  dist.clear();
  dfs(U);
  for(auto e : dist){
    int node = e.first;
    int dis = e.second;
    if(dis > mx){
      mx = dis;
      V = node;
    }
  }
  dist.clear();
  dfs_(U, V);
  return centre(U, V)[0];
}
/*
12 8 2
0 8 4
8 2 2
2 7 4
5 11 3
5 1 7
1 3 1
1 9 5
10 6 3
*/

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