Submission #116925

#	Time	Username	Problem	Language	Result	Execution time	Memory
116925		dragonslayerit	Dreaming (IOI13_dreaming)	C++14	100 / 100	146 ms	22136 KiB

dreaming

#include "dreaming.h"
#include <vector>
#include <algorithm>
#include <functional>
#include <cstdio>

const int INF=1e9+7;

std::vector<std::pair<int,int> > adj[100005];
int vis[100005];
std::vector<std::pair<int,int> > down[100005];
int solo=0;

void dfs1(int node){
  vis[node]=1;
  down[node].push_back({0,node});
  for(auto e:adj[node]){
    int child=e.first;
    if(vis[child]==1) continue;
    dfs1(child);
    down[node].push_back({down[child][0].first+e.second,child});
  }
  std::sort(down[node].begin(),down[node].end(),std::greater<std::pair<int,int> >());
  if(down[node].size()>=2){
    solo=std::max(solo,down[node][0].first+down[node][1].first);
  }
}

void dfs2(int node,int up,int& far){
  vis[node]=2;
  far=std::min(far,std::max(up,down[node][0].first));
  solo=std::max(solo,up+down[node][0].first);
  for(auto e:adj[node]){
    int child=e.first;
    if(vis[child]==2) continue;
    dfs2(child,std::max(up,down[node][child==down[node][0].second].first)+e.second,far);
  }
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
  for(int i=0;i<M;i++){
    adj[A[i]].push_back({B[i],T[i]});
    adj[B[i]].push_back({A[i],T[i]});
  }
  std::vector<int> trees;
  for(int i=0;i<N;i++){
    if(!vis[i]){
      int far=INF;
      dfs1(i);
      dfs2(i,0,far);
      trees.push_back(far);
      //fprintf(stderr,"TREE: %d\n",far);
    }
  }
  std::sort(trees.begin(),trees.end(),std::greater<int>());
  int ans=solo;
  if(trees.size()>=2){
    ans=std::max(ans,trees[0]+trees[1]+L);
  }
  if(trees.size()>=3){
    ans=std::max(ans,trees[1]+trees[2]+L*2);
  }
  return ans;
}

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