#include "highway.h"
#include <bits/stdc++.h>
//#include "grader.cpp"
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
int n,m,niv[100005],par[100005],topar[100005],dp[21][100005],in[100005],out[100005],timp;
ll dist;
vector<pii> muchii[100005];
vector<pii> g;
vector<int> w;
bool isancestor(int a,int b)
{
return in[a]<=in[b]&&out[a]>=out[b];
}
int LCA(int a,int b)
{
if(niv[a]>niv[b])
swap(a,b);
if(isancestor(a,b))
return a;
for(int i=20;i>=0;i--)
if(dp[i][a]!=-1&&!isancestor(dp[i][a],b))
a=dp[i][a];
return par[a];
}
void dfs(int nod)
{
timp++;
in[nod]=timp;
dp[0][nod]=par[nod];
for(int i=1;i<=20;i++)
{
if(dp[i-1][nod]==-1)
{
dp[i][nod]=-1;
continue;
}
dp[i][nod]=dp[i-1][dp[i-1][nod]];
}
for(auto i:muchii[nod])
if(i.first!=par[nod])
{
par[i.first]=nod;
niv[i.first]=niv[nod]+1;
topar[i.first]=i.second;
dfs(i.first);
}
out[nod]=timp;
}
void buildniv(int p)
{
for(int i=0;i<m;i++)
{
w[i]=1;
if(min(niv[g[i].first],niv[g[i].second])<=p)
w[i]=0;
}
}
int getnode(vector<int> cand)
{
while(true)
{
if(cand.size()==1)
return cand[0];
vector<int> x,y;
int lg=cand.size();
for(int i=0;i<cand.size();i++)
{
if(i<lg/2)
x.push_back(cand[i]);
else
y.push_back(cand[i]);
}
for(int i=0;i<m;i++)
w[i]=1;
for(int i:x)
w[topar[i]]=0;
ll val=ask(w);
if(val<dist*B)
cand=x;
else
cand=y;
}
return -1;
}
void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B)
{
n=N;
m=U.size();
for(int i=0;i<m;i++)
{
int a=U[i],b=V[i];
g.push_back({a,b});
muchii[a].push_back({b,i});
muchii[b].push_back({a,i});
}
for(int i=0;i<n;i++)
par[i]=-1;
niv[0]=1;
dfs(0);
int nivmax=0;
for(int i=0;i<n;i++)
nivmax=max(nivmax,niv[i]);
for(int i=0;i<m;i++)
w.push_back(0);
dist=ask(w)/A;
int nivlca=nivmax;
int st=1;
int dr=nivmax-1;
while(st<=dr)
{
int mij=(st+dr)/2;
buildniv(mij);
ll val=ask(w);
if(val<dist*B)
{
nivlca=mij;
dr=mij-1;
}
else
st=mij+1;
}
int nivS=nivlca;
int nivT=0;
st=nivlca;
dr=nivmax;
while(st<=dr)
{
int mij=(st+dr)/2;
buildniv(mij);
ll nra=2*(mij-nivlca);
if(nra<=dist)
{
ll val=ask(w);
buildniv(mij-1);
ll val2=ask(w);
if(val2==val+2LL*(B-A))
{
nivS=mij+1;
st=mij+1;
continue;
}
}
dr=mij-1;
}
nivT=nivlca+(dist-(nivS-nivlca));
vector<int> c1,c2;
if(nivS==nivT)
{
vector<int> cand;
for(int i=0;i<n;i++)
if(niv[i]==nivS)
cand.push_back(i);
while(true)
{
if(cand.size()==2)
{
c1.push_back(cand[0]);
c2.push_back(cand[1]);
break;
}
vector<int> x,y;
int lg=cand.size();
for(int i=0;i<cand.size();i++)
{
if(i<lg/2)
x.push_back(cand[i]);
else
y.push_back(cand[i]);
}
for(int i=0;i<m;i++)
w[i]=1;
for(int i:x)
w[topar[i]]=0;
ll val=ask(w);
if(val==1LL*(dist-2)*B+2LL*A)
{
cand=x;
continue;
}
if(val==dist*B)
{
cand=y;
continue;
}
c1=x;
c2=y;
break;
}
}
else
{
for(int i=0;i<n;i++)
{
if(niv[i]==nivS)
c1.push_back(i);
if(niv[i]==nivT)
c2.push_back(i);
}
}
int T=getnode(c2);
c1.clear();
for(int i=0;i<n;i++)
if(niv[i]==nivS&&niv[LCA(i,T)]==nivlca)
c1.push_back(i);
int S=getnode(c1);
answer(S,T);
}
Compilation message
highway.cpp: In function 'int getnode(std::vector<int>)':
highway.cpp:68:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
68 | for(int i=0;i<cand.size();i++)
| ~^~~~~~~~~~~~
highway.cpp:80:21: error: 'B' was not declared in this scope
80 | if(val<dist*B)
| ^
highway.cpp: In function 'void find_pair(int, std::vector<int>, std::vector<int>, int, int)':
highway.cpp:165:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
165 | for(int i=0;i<cand.size();i++)
| ~^~~~~~~~~~~~
