#include <fstream>
#include <vector>
#include <algorithm>
#include <cstring>
#define DIM 100010
#define INF 2000000000
#include "dreaming.h"
using namespace std;
ifstream fin ("dreaming.in");
ofstream fout ("dreaming.out");
int nr,n,m,l,i;
int dp_down[DIM]; /// cel mai lung drum in subarborele lui i
int dp_up[DIM]; /// cel mai lung drum din i in afara subarborelui lui i
int s[DIM],viz[DIM],v[DIM],a[DIM],b[DIM],cost[DIM];
vector <pair<int,int> > L[DIM];
vector <int> comp[DIM];
void dfs (int nod, int tata){
viz[nod] = 1;
comp[nr].push_back(nod);
for (int i=0;i<L[nod].size();i++){
int vecin = L[nod][i].first;
if (vecin != tata){
dfs (vecin,nod);
s[nod] = max (s[nod],s[vecin]+L[nod][i].second);
}}
int maxim = 0, maxim2 = 0;
for (int i=0;i<L[nod].size();i++){
int vecin = L[nod][i].first, cost = L[nod][i].second;
if (vecin == tata)
continue;
if (s[vecin]+cost > maxim){
maxim2 = maxim;
maxim = s[vecin]+cost;
} else {
if (s[vecin]+cost > maxim2)
maxim2 = s[vecin]+cost;
}}
dp_down[nod] = maxim+maxim2;
}
void dfs2 (int nod, int tata, int cost){
dp_up[nod] = max (dp_up[nod],dp_up[tata]+cost);
int maxim = 0, maxim2 = 0, p = 0;
for (int i=0;i<L[nod].size();i++){
int fiu = L[nod][i].first, cst = L[nod][i].second;
if (fiu == tata)
continue;
if (s[fiu]+cst > maxim){
maxim2 = maxim;
maxim = s[fiu]+cst, p = fiu;
} else
if (s[fiu]+cst > maxim2)
maxim2 = s[fiu]+cst;
}
for (int i=0;i<L[nod].size();i++){
int fiu = L[nod][i].first;
if (fiu == tata)
continue;
if (fiu == p)
dp_up[fiu] = max (dp_up[fiu],maxim2+L[nod][i].second);
else dp_up[fiu] = max (dp_up[fiu],maxim+L[nod][i].second);
}
for (int i=0;i<L[nod].size();i++){
int vecin = L[nod][i].first;
if (vecin != tata)
dfs2 (vecin,nod,L[nod][i].second);
}}
int timeTravel (int n, int m, int l, int a[], int b[], int cost[]){
for (int i=1;i<=n;i++)
L[i].clear();
for (int i=0;i<m;i++){
int x = a[i], y = b[i], cst = cost[i];
x++, y++;
L[x].push_back(make_pair(y,cst));
L[y].push_back(make_pair(x,cst));
}
memset (viz,0,sizeof viz);
memset (dp_up,0,sizeof dp_up);
memset (dp_down,0,sizeof dp_down);
memset (s,0,sizeof s);
nr = 0;
for (int i=1;i<=n;i++){
if (!viz[i]){
nr++;
dfs (i,0);
dfs2 (i,0,0);
}}
int sol = 0;
for (int i=1;i<=nr;i++){
/// incerc sa aleg cel mai bun nod reprezentant pt componenta conexa i
int mini = INF;
for (auto nod:comp[i]){
/// distanta maxima in componenta i
int dist_max = max (dp_up[nod]+s[nod],dp_down[nod]);
sol = max (sol,dist_max);
/// incerc sa l aleg pe nod reprezentant
int dist = max (s[nod],dp_up[nod]);
mini = min (mini,dist);
}
v[i] = mini;
}
sort (v+1,v+nr+1);
if (nr >= 2)
sol = max (sol,v[nr-1]+v[nr]+l);
if (nr >= 3)
sol = max (sol,v[nr-1]+v[nr-2]+2*l);
return sol;
}
Compilation message
dreaming.cpp: In function 'void dfs(int, int)':
dreaming.cpp:20:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int i=0;i<L[nod].size();i++){
~^~~~~~~~~~~~~~
dreaming.cpp:27:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int i=0;i<L[nod].size();i++){
~^~~~~~~~~~~~~~
dreaming.cpp: In function 'void dfs2(int, int, int)':
dreaming.cpp:44:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int i=0;i<L[nod].size();i++){
~^~~~~~~~~~~~~~
dreaming.cpp:55:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int i=0;i<L[nod].size();i++){
~^~~~~~~~~~~~~~
dreaming.cpp:64:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int i=0;i<L[nod].size();i++){
~^~~~~~~~~~~~~~
/tmp/ccdE2Zgb.o: In function `main':
grader.c:(.text.startup+0xa2): undefined reference to `travelTime'
collect2: error: ld returned 1 exit status
