Submission #14771

#	Time	Username	Problem	Language	Result	Execution time	Memory
14771		progressive	Dreaming (IOI13_dreaming)	C++98	100 / 100	105 ms	16244 KiB

dreaming

#include "dreaming.h"
#include <vector>
#include <algorithm>
using namespace std;

static const int MAXN=100100;
static vector<pair<int,int> > conn[MAXN];
static int color[MAXN];
static int tp=0;
static int hdist[MAXN];
static int dist[MAXN];
static int parent[MAXN];
static vector<int> samecolor[MAXN];
static vector<int> radius;
void colordfs(int a,int pa,int c)
{
	color[a]=c;
	samecolor[c].push_back(a);
	for(int i=0;i<conn[a].size();i++)
	{
		int target=conn[a][i].first;
		if(target==pa) continue;
		hdist[target]=hdist[a]+conn[a][i].second;
		colordfs(target,a,c);
	}
}
void dfs(int a,int pa)
{
	parent[a]=pa;
	for(int i=0;i<conn[a].size();i++)
	{
		int target=conn[a][i].first;
		if(target==pa) continue;
		dist[target]=dist[a]+conn[a][i].second;
		dfs(target,a);
	}
}
int travelTime(int N, int M, int L, int A[], int B[], int T[])
{
	tp=0;
	radius.clear();
	for(int i=0;i<MAXN;i++)
	{
		conn[i].clear();
		color[i]=0;
		hdist[i]=0;
		dist[i]=0;
		parent[i]=0;
		samecolor[i].clear();
	}
	for(int i=0;i<M;i++)
	{
		conn[A[i]].push_back(make_pair(B[i],T[i]));
		conn[B[i]].push_back(make_pair(A[i],T[i]));
	}
	for(int i=0;i<N;i++)
		if(!color[i]) colordfs(i,-1,++tp);
	int retval=0;
	for(int i=1;i<=tp;i++)
	{
		int furthest=samecolor[i][0];
		for(int j=0;j<samecolor[i].size();j++)
			if(hdist[furthest]<hdist[samecolor[i][j]]) furthest=samecolor[i][j];
		dfs(furthest,-1);
		int dia=furthest;
		for(int j=0;j<samecolor[i].size();j++)
			if(dist[dia]<dist[samecolor[i][j]]) dia=samecolor[i][j];
		int radii=dist[dia];
		int res=radii;
		retval=max(retval,radii);
		while(dia!=-1)
		{
			res=min(res,max(radii-dist[dia],dist[dia]));
			dia=parent[dia];
		}
		radius.push_back(res);
	}
	sort(radius.begin(),radius.end());
	reverse(radius.begin(),radius.end());
	if(tp==2) retval=max(retval, radius[0]+radius[1]+L);
	else if(tp>2) retval=max(retval,max(radius[0]+radius[1]+L,radius[1]+radius[2]+2*L));
	return retval;
}

Compilation message (stderr)

dreaming.cpp: In function 'void colordfs(int, int, int)':
dreaming.cpp:19:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<conn[a].size();i++)
              ~^~~~~~~~~~~~~~~
dreaming.cpp: In function 'void dfs(int, int)':
dreaming.cpp:30:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<conn[a].size();i++)
              ~^~~~~~~~~~~~~~~
dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:62:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<samecolor[i].size();j++)
               ~^~~~~~~~~~~~~~~~~~~~
dreaming.cpp:66:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0;j<samecolor[i].size();j++)
               ~^~~~~~~~~~~~~~~~~~~~

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