#include <bits/stdc++.h>
#include <random>
#include <chrono>
using namespace std;
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<double,double> pdd;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
template<typename T> void _do(T x){cerr<<x<<"\n";}
template<typename T,typename ...U> void _do(T x,U ...y){cerr<<x<<", ";_do(y...);}
#define dbg(...) cerr<<#__VA_ARGS__<<" = ";_do(__VA_ARGS__);
const int MOD1=1e9+7;
const int MOD2=998244353;
const ll INF=3e18;
ll fpow(ll a,ll b,ll m)
{
if(!b) return 1;
ll tmp=1;
for(ll cur=a;b;b>>=1,cur=cur*cur%m) if(b&1) tmp=tmp*cur%m;
return tmp;
}
ll inv(ll a,ll m) {return fpow(a,m-2,m);}
#define MottoHayaku ios::sync_with_stdio(false);cin.tie(0);
#define rep(i,n) for(int i=0;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define F first
#define S second
#define pb push_back
#define uni(c) c.resize(distance(c.begin(),unique(c.begin(),c.end())))
#define unisort(c) sort(c.begin(),c.end()),uni(c)
bool has[300][300];
vector<int> ed[300];
bool vis[300];
int par[300];
int deg[300],cnt[300];
int n;
void dfs(int u)
{
vis[u]=1;
for(int v:ed[u]) if(!vis[v])
{
par[v]=u;
cnt[u]++;
dfs(v);
}
}
void dfs2(int u,vector<int> &ret)
{
vis[u]=1;
ret.pb(u);
for(int v:ed[u]) if(!vis[v]) dfs2(v,ret);
}
/*bool db[300][300];
bool are_connected(vector<int> a,vector<int> b)
{
bool ret=0;
for(int x:a) for(int y:b)
{
ret|=db[x][y];
}
return ret;
}*/
vector<int> longest_trip(int N,int D)
{
n=N;
vector<int> ret;
if(D==3)
{
rep(i,n) ret.pb(i);
return ret;
}
rep(i,n) rep(j,i)
{
bool res=are_connected({i},{j});
if(res)
{
ed[i].pb(j);
ed[j].pb(i);
has[i][j]=has[j][i]=1;
deg[i]++,deg[j]++;
}
}
par[0]=-1;
dfs(0);
vector<int> a,b;
rep(i,n)
{
if(vis[i]) a.pb(i);
else b.pb(i);
}
if(!b.empty())
{
if(a.size()>b.size()) return a;
else return b;
}
int r=-1;
rep(i,n)
{
vis[i]=0;
if(deg[i]==1) r=i;
}
if(r!=-1)
{
dfs2(r,ret);
return ret;
}
vector<int> tmp;
int x;
rep(i,n)
{
if(cnt[i]==0) tmp.pb(i);
if(cnt[i]==2) x=i;
}
if(tmp.size()==1)
{
int cur=tmp[0];
while(cur!=-1)
{
ret.pb(cur);
cur=par[cur];
}
return ret;
}
vector<int> ret2;
int cur=tmp[0];
while(cur!=par[x])
{
ret.pb(cur);
cur=par[cur];
}
cur=tmp[1];
while(cur!=x)
{
ret2.pb(cur);
cur=par[cur];
}
reverse(ret2.begin(),ret2.end());
for(int v:ret2) ret.pb(v);
if(x==0) return ret;
vector<int> ret3;
cur=par[x];
while(cur!=-1)
{
ret3.pb(cur);
cur=par[cur];
}
if(has[par[x]][tmp[0]])
{
reverse(ret.begin(),ret.end());
}
for(int v:ret3) ret.pb(v);
return ret;
}
/*
void solve()
{
int N,D;
cin>>N>>D;
rep(i,N)
{
rep(j,N) cin>>db[i][j];
}
auto ans=longest_trip(N,D);
for(int x:ans) cout<<x<<" ";
}
signed main()
{
MottoHayaku
int t;
//cin>>t;
t=1;
while(t--)
{
solve();
}
}*/
Compilation message
longesttrip.cpp: In function 'std::vector<int> longest_trip(int, int)':
longesttrip.cpp:91:18: error: 'are_connected' was not declared in this scope
91 | bool res=are_connected({i},{j});
| ^~~~~~~~~~~~~
