//#include"dreaming.h"
#include<bits/stdc++.h>
using namespace std;
int fix[500005], mx, l, ans, k, x, y;
vector<pair<int, int> >v[500005];
vector<int>vec;
stack<int>s;
void dfs(int x, int y, int z){
fix[x]=1;
if(mx<z){
mx=z;
l=x;
}
for(int i=0; i<v[x].size(); i++)
if(v[x][i].first==y) continue;
else dfs(v[x][i].first, x, z+v[x][i].second);
}
void dfs1(int x, int y, int z, int p){
if(z!=-1 && k==0) s.push(v[z][p].second);
for(int i=0; i<v[x].size(); i++)
if(v[x][i].first==z) continue;
else dfs1(v[x][i].first, y, x, i);
if(x==y) k=1;
if(k==0) s.pop();
}
int travelTime(int N, int M, int L, int A[], int B[], int T[]){
for(long long i=0; i<M; i++) {
v[A[i]].push_back({B[i], T[i]});
v[B[i]].push_back({A[i], T[i]});
}
for(long long i=0; i<N; i++){
if(fix[i]!=0) continue;
mx=0;
l=-1;
dfs(i, l, mx);
x=l;
mx=0;
l=-1;
dfs(x, l, mx);
y=l;
ans=max(ans, mx);
k=0;
dfs1(x, y, -1, 0);
if(s.empty()) vec.push_back(0);
x=0;
while(!s.empty()){
x+=s.top();
if(x==mx/2 && mx%2==0){
vec.push_back(mx/2);
break;
}
else if(x>mx/2){
vec.push_back(min(x, max(x-s.top(), mx-x+s.top())));
break;
}
s.pop();
}
while(!s.empty()) s.pop();
}
sort(vec.begin(), vec.end());
if(vec.size()>=2) ans=max(ans, vec[vec.size()-1]+vec[vec.size()-2]+L);
if(vec.size()>=3) ans=max(ans, vec[vec.size()-2]+vec[vec.size()-3]+2*L);
return ans;
}
Compilation message
dreaming.cpp: In function 'void dfs(int, int, int)':
dreaming.cpp:14:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
14 | for(int i=0; i<v[x].size(); i++)
| ~^~~~~~~~~~~~
dreaming.cpp: In function 'void dfs1(int, int, int, int)':
dreaming.cpp:20:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
20 | for(int i=0; i<v[x].size(); i++)
| ~^~~~~~~~~~~~
/tmp/ccH5OsP7.o: In function `main':
grader.c:(.text.startup+0xc9): undefined reference to `travelTime'
collect2: error: ld returned 1 exit status
