Submission #1828

#	Time	Username	Problem	Language	Result	Execution time	Memory
1828		kriii	Dreaming (IOI13_dreaming)	C++98	100 / 100	103 ms	8604 KiB

dreaming

#include "dreaming.h"
#include <algorithm>
#include <vector>
#include <queue>
using namespace std;
#define max_N 100010

vector<pair<int, int> > Graph[max_N];
vector<int> Radius;

int Dist[max_N],Chk[max_N];

int FindEnd(int start, int chked)
{
	queue<int> Q; int i,x,y,far,ind;
	Q.push(start); Dist[start] = 0; Chk[start] = chked;
	far = 0; ind = start;
	while (!Q.empty()){
		x = Q.front(); Q.pop();

		for (i=0;i<Graph[x].size();i++){
			y = Graph[x][i].first;
			if (Chk[y] != chked){
				Q.push(y); Dist[y] = Dist[x] + Graph[x][i].second; Chk[y] = chked;
				if (far < Dist[y]){
					far = Dist[y]; ind = y;
				}
			}
		}
	}

	return ind;
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
	int i,j,x,y,ans=0,now,end;

	for (i=0;i<M;i++){
		x = A[i]; y = B[i];
		Graph[x].push_back(make_pair(y,T[i]));
		Graph[y].push_back(make_pair(x,T[i]));
	}

	for (i=0;i<N;i++) if (Chk[i] == 0){
		y = FindEnd(i,1);
		x = FindEnd(y,2);
		
		now = end = Dist[x];
		if (ans < end) ans = end;

		while (Dist[x] > 0){
			for (j=0;j<Graph[x].size();j++){
				y = Graph[x][j].first;
				if (Dist[x] == Dist[y] + Graph[x][j].second){
					x = y; break;
				}
			}
			now = min(now,max(Dist[x],end-Dist[x]));
		}

		Radius.push_back(now);
	}

	sort(Radius.rbegin(),Radius.rend());
	if (Radius.size() == 2) ans = max(ans,Radius[0]+Radius[1]+L);
	else if (Radius.size() > 2){
		int last = max(Radius[0]+Radius[1],Radius[1]+Radius[2]+L);
		last = min(max(Radius[1]+Radius[0],Radius[0]+Radius[2]+L),last);
		last = min(max(Radius[2]+Radius[0],Radius[0]+Radius[1]+L),last);
		ans = max(ans,last+L);
	}

	return ans;
}

Compilation message (stderr)

dreaming.cpp: In function 'int FindEnd(int, int)':
dreaming.cpp:21:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (i=0;i<Graph[x].size();i++){
            ~^~~~~~~~~~~~~~~~
dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:52:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (j=0;j<Graph[x].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