#include <bits/stdc++.h>
using namespace std;
const int N=240000+7;
int n;
int k;
vector<pair<int, int>> gg[N];
vector<pair<int,int>> q2[N];
vector<int> q1[N];
const int K = 20;
int p[N];
int pskip[K][N];
int dep[N];
int euler_tour[2 * N];
int tour_sz;
int first_time_on_tour[N];
int last_time_on_tour[N];
int lg2[2 * N];
int idup[N];
//vector<int> g[N];
pair<int, int> tab_lca[2 * N][K];
void dfs_lca(int a, int par = 0)
{
p[a] = par;
euler_tour[++tour_sz] = a;
first_time_on_tour[a] = last_time_on_tour[a] = tour_sz;
for (auto &it : gg[a])
{
int b=it.first;
int i=it.second;
if (b==par){
continue;
}
idup[b]=i;
dep[b] = 1 + dep[a];
dfs_lca(b, a);
euler_tour[++tour_sz] = a;
last_time_on_tour[a] = tour_sz;
}
}
void lcaTM()
{
dfs_lca(1);
for (int i = 2; i <= tour_sz; i++)
{
lg2[i] = 1 + lg2[i / 2];
}
for (int i = 1; i <= tour_sz; i++)
{
tab_lca[i][0] = {dep[euler_tour[i]], euler_tour[i]};
}
for (int k = 1; (1 << k) <= tour_sz; k++)
{
for (int i = 1; i + (1 << k) - 1 <= tour_sz; i++)
{
tab_lca[i][k] = min(tab_lca[i][k - 1], tab_lca[i + (1 << (k - 1))][k - 1]);
}
}
}
int lca(int a, int b)
{
if (first_time_on_tour[a] > last_time_on_tour[b])
{
swap(a, b);
}
a = first_time_on_tour[a];
b = last_time_on_tour[b];
int k = lg2[b - a + 1];
return min(tab_lca[a][k], tab_lca[b - (1 << k) + 1][k]).second;
}
int goup(int a,int cnt){
assert(cnt>=0);
for(int i=0;i<K;i++){
if(cnt&(1<<i)){
a=pskip[i][a];
}
}
return a;
}
int sol[N];
int tp[N];
int inc[N];
int dcr[N];
void dfs2(int a){
inc[a]=max(inc[a],1);
dcr[a]=max(dcr[a],1);
for (auto &it:gg[a]){
int b=it.first;
if(b==p[a]){
continue;
}
if(idup[a]<idup[b]){
inc[b]=1+inc[a];
}else{
dcr[b]=1+dcr[a];
}
dfs2(b);
}
///cout<<"vis "<<a<<" : "<<inc[a]<<" vs "<<dcr[a]<<"\n";
}
int main() {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
/// freopen("___input___.txt","r",stdin);
cin>>n>>k;
for(int i=1;i<=n+k-1;i++){
string s;
cin>>s;
assert(s=="S"||s=="Q"||s=="C");
if(s=="S"){
int a,b;
cin>>a>>b;
///g[a].push_back(b);
///g[b].push_back(a);
gg[a].push_back({b, i});
gg[b].push_back({a, i});
sol[i]=-1;
}
if(s=="Q"){
int a,b;
cin>>a>>b;
if(a==b){
tp[i]=1;
sol[i]=1;
}else{
q2[a].push_back({b, i});
tp[i]=1;
sol[i]=-2;
}
}
if(s=="C"){
int a;
cin>>a;
q1[a].push_back(i);
sol[i]=-3;
}
}
lcaTM();
dfs2(1);
/// solve q1 for the general case
for (int i=1;i<=n;i++){
pskip[0][i]=p[i];
}
for (int k=1;k<K;k++){
for (int i=1;i<=n;i++){
pskip[k][i]=pskip[k-1][pskip[k-1][i]];
}
}
for (int a=1;a<=n;a++){
for (auto &it:q2[a]){
int b=it.first,i=it.second;
/**
**/
/// drumul de la b la a e crescator?
vector<int> guys_x,guys_y;
int x=a,y=b,z;
swap(x,y);
z=lca(x,y);
int last=-1;
if(y!=z){
last=idup[y];
}else{
// cout<<"ici\n";
assert(x!=z);
assert(dep[x]-dep[z]-1>=0);
// cout<<x << " : "<<dep[x]-dep[z]-1<<"\n";
int vlx=goup(x,dep[x]-dep[z]-1);
assert(p[vlx]==z);
last=idup[vlx];
}
bool ok=1;
ok&=(inc[y]>=dep[y]-dep[z]);
ok&=(dcr[x]>=dep[x]-dep[z]);
if(x!=z&&y!=z){
ok&=(idx[goup(x,dep[x]-dep[z]-1)]<=idup[y]);
}
while (x!=z){
guys_x.push_back(idup[x]);
x=p[x];
}
while(y!=z){
guys_y.push_back(idup[y]);
y=p[y];
}
vector<int> guys=guys_x;
reverse(guys_y.begin(),guys_y.end());
for (auto &V:guys_y){
guys.push_back(V);
}
assert(!guys.empty());
assert(guys.back()==last);
if(!guys_x.empty()&&!guys_y.empty()){
// ok&=(guys_x.back()<=guys_y[0]);
}
ok&=(guys.back()<i);
sol[i]=ok;
}
}
for (int i=1;i<=n+k-1;i++){
if(tp[i]==1){
assert(sol[i]==0||sol[i]==1);
if(sol[i]==1){
cout<<"yes\n";
}else{
cout<<"no\n";
}
}
}
return 0;
}
Compilation message
servers.cpp: In function 'int main()':
servers.cpp:190:38: error: 'idx' was not declared in this scope
190 | ok&=(idx[goup(x,dep[x]-dep[z]-1)]<=idup[y]);
| ^~~
