Submission #29798

#	Time	Username	Problem	Language	Result	Execution time	Memory
29798		kavun	Dreaming (IOI13_dreaming)	C++14	100 / 100	133 ms	14200 KiB

dreaming

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

using namespace std;
typedef pair<int,int> ii;
vector <ii> adj[100010];
bool mk[100010];
int maxDist, ennd,ans;
ii p[100010];
vector <int> r;

void dfs(int v, int par, int len, int flag)
{
  if(flag)
    mk[v] = true;

  if(len > maxDist)
    {
      maxDist = len;
      ennd = v;
    }

  for(int i = 0; i < adj[v].size(); i++)
    {
      int u = adj[v][i].first;
      if(u == par) continue;
      int weight = adj[v][i].second;
      if(flag)
	p[u] = ii(v,weight);
      dfs(u,v,len+weight,flag);
    }
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
  for(int i = 0; i < M; i++)
    {
      adj[A[i]].pb(ii(B[i],T[i]));
      adj[B[i]].pb(ii(A[i],T[i]));
    }

  for(int i = 0; i < N; i++)
    {
      if(mk[i]) continue;
      maxDist = -1;
      dfs(i,i,0,0);
      maxDist = -1;
      int first = ennd;
      dfs(first,first,0,1);
      ans = max(ans,maxDist);
      int second = ennd;
      int halfdiam = maxDist / 2;
      int radius = 0;
      for(int ver = second; ver != first; ver = p[ver].first)
	{
	  if(radius + p[ver].second > halfdiam)
	    {
	      radius = min(radius + p[ver].second,maxDist - radius);
	      break;
	    }
	  radius += p[ver].second;
	}
      r.pb(radius);
    }
    
  sort(r.begin(),r.end());
  reverse(r.begin(),r.end());

  if(r.size() == 1)
    return ans;
  if(r.size() == 2) 
    return max(ans,r[0] + r[1] + L);
  else 
    return max(ans,max(r[1] + r[2] + L + L,r[0] + r[1] + L));

}

Compilation message (stderr)

dreaming.cpp: In function 'void dfs(int, int, int, int)':
dreaming.cpp:24:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 0; i < adj[v].size(); i++)
                  ~~^~~~~~~~~~~~~~~

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