// #include "dreaming.h"
#include <iostream>
#include <vector>
using namespace std;
const long long N=1e5+200;
vector<pair<long long,long long>> ma[N];
bool vis[N];
bool tp=0;
long long dp_down[N][2];
long long dp_up[N];
long long mxx[N];
long long n,m,l;
void dfs_down(long long x,long long p=-1)
{
vis[x]=1;
dp_down[x][0]=dp_down[x][1]=0;
for(auto [w,y]:ma[x])
{
if(y!=p)
{
dfs_down(y,x);
long long cur=dp_down[y][0]+w;
if(dp_down[x][0]<cur)
{
dp_down[x][1]=dp_down[x][0];
dp_down[x][0]=cur;
}
else if(dp_down[x][1]<cur)
{
dp_down[x][1]=cur;
}
}
}
// if(tp)
// {
// cout<<"For "<<x<<' '<<p<<endl;
// cout<<dp_down[x][0]<<' '<<dp_down[x][1]<<endl;
// }
}
long long vertex=-1;
long long dist=1e18;
long long cp=-1;
void fill()
{
for(int i=0;i<n;i++)
dp_up[i]=0;
}
void dfs_up(long long x,long long p=-1)
{
mxx[x]=max(dp_up[x],dp_down[x][0]);
cp=max(cp,mxx[x]);
// if(tp)
// {
// cout<<"For "<<x<<' '<<mxx[x]<<endl;
// }
if(mxx[x]<dist)
{
dist=mxx[x];
vertex=x;
}
for(auto [w,y]:ma[x])
{
if(y!=p)
{
dp_up[y]=dp_up[x]+w;
if(dp_down[x][0]==(dp_down[y][0]+w))
dp_up[y]=max(dp_up[y],dp_down[x][1]+w);
else
dp_up[y]=max(dp_up[y],dp_down[x][0]+w);
dfs_up(y,x);
}
}
}
int travelTime(int N, int M, int L, int a[], int b[], int t[])
{
n=N;
m=M;
l=L;
for(int i=0;i<m;i++)
{
ma[a[i]].push_back({t[i],b[i]});
ma[b[i]].push_back({t[i],a[i]});
}
for(int i=0;i<n;i++)
{
if(!vis[i]){
long long bv=vertex;
long long bd=dist;
vertex=-1;
dist=1e18;
dfs_down(i);
dfs_up(i);
if(bv!=-1)
{
ma[bv].push_back({l,vertex});
ma[vertex].push_back({l,bv});
long long stp=vertex;
vertex=-1;
dist=1e18;
dfs_down(stp);
fill();
dfs_up(stp);
}
}
}
cp=-1;
tp=1;
dfs_down(0);
fill();
dfs_up(0);
// cout<<"adj\n";
// for(int i=0;i<n;i++)
// {
// cout<<"For "<<i<<' ';
// for(auto [j,p]:ma[i]){
// cout<<p<<' ';
// }
// cout<<endl;
// cout<<"a\n";
// }
return cp;
}
Compilation message
dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:88:14: warning: unused variable 'bd' [-Wunused-variable]
88 | long long bd=dist;
| ^~
/usr/bin/ld: /tmp/ccteHgzX.o: in function `main':
grader.c:(.text.startup+0xd1): undefined reference to `travelTime'
collect2: error: ld returned 1 exit status
