#include <bits/stdc++.h>
using namespace std;
int n,m;
vector <vector <int> > InComponents;
vector <vector <int> > adj; //the edge list of the KRT
vector <int> TVector;
int RootID; //ID of the root node of the KRT;
struct Edge{
long long Weight;
int Start;
int End;
};
bool operator< (const Edge &x, const Edge &y){
return x.Weight<y.Weight;
}
Edge Elist[500003];
int Depth[500003];
int Deg[500003];
int CurRep[500003]; //id of the respresentative node on the KRT
int Par[500003]; //Parent of node with id i on the KRT;
int Toggle[500003]; //is the i-th node on the KRT toggled?
int Check[500003];
int Ancestor[500003][20];
long long Val[500003];//the value of the i-th node of the KRT
vector <int> KRTID;
int GetRep(int u){
if(CurRep[u]==u){
return u;
}else{
return CurRep[u]=GetRep[RepU];
}
}
void DSU(int id, int u, int v, int w){
Deg[u]++;
Deg[v]++;
//u and v belongs to the same component. The component now has a cycle. Immediately toggle the root node of the current
//subtree that includes both u and v on the KRT
int RepU=GetRep(u), RepV=GetRep(v);
if(RepU==RepV){
//The node isn't toggled just yet. Toggle it immediately
if(!Toggle[RepU]){
Toggle[RepU]=1;
Val[RepU]=w;
}else{
//The node is already toggled by an edge with lower edge. Only a fucking dumbass would touch it - already minimized
//toggle value. Just leave it alone
}
}else{
//u and v doesn't belong to the same component. Merge them
int CurID=n-1+id;
int OldComp1=RepU, OldComp2=RepV;
adj[RepU].push_back(CurID);
adj[RepV].push_back(CurID);
adj[CurID].push_back(RepU);
adj[CurID].push_back(RepV);
Par[RepU]=CurID;
Par[RepV]=CurID;
//if either of the components are toggled already (having a cycle OR a vertex with degree >3)
//OR the merged component has a vertex with degree >3 (either u or v), toggle immediately
if(Toggle[OldComp1]||Toggle[OldComp2]||Deg[u]>2||Deg[v]>2){
Toggle[CurID]=1;
}
KRTID.push_back(CurID);
RootID=CurID;
}
}
void init(int N, int M, vector <int> U, vector <int> V, vector <int> W){
n=N;
m=M;
for(int i=0;i<n+m+5;i++){
InComponents.push_back(TVector);
adj.push_back(TVector);
}
for(int i=1;i<=m;i++){
Elist[i].Weight=W[i-1];
Elist[i].Start=U[i-1];
Elist[i].End=V[i-1];
}
sort(Elist+1,Elist+m+1);
for(int i=0;i<=m+n+1;i++){
CurRep[i]=i;
}
for(int i=0;i<n;i++){
CurRep[i]=i;
InComponents[i].push_back(i);
KRTID.push_back(i);
}
for(int i=1;i<=m;i++){
DSU(i,Elist[i].Start,Elist[i].End,Elist[i].Weight);
}
//The KRT is now built. BFS from the root node and initialize LCA or something
deque <int> dq;
dq.push_back(RootID);
Check[RootID]=1;
int Cur;
while(!dq.empty()){
Cur=dq.front();
for(int i=0;i<adj[Cur].size();i++){
if(!Check[adj[Cur][i]]){
dq.push_back(adj[Cur][i]);
Check[adj[Cur][i]]=1;
Depth[adj[Cur][i]]=Depth[Cur]+1;
}
}
dq.pop_front();
}
Par[RootID]=500000;
Par[500000]=500000;
Toggle[500000]=1;
for(int i=0;i<=19;i++){
for(int k=0;k<KRTID.size();k++){
if(i==0){
Ancestor[KRTID[k]][i]=Par[KRTID[k]];
}else{
Ancestor[KRTID[k]][i]=Ancestor[Ancestor[KRTID[k]][i-1]][i-1];
}
}
}
}
int getMinimumFuelCapacity(int x, int y){
//I thought that we actually need to use binary lifting to find LCA and then jump from the LCA to find the nearest
//toggled node on the KRT
//But apparently small-to-large merging ensures that the depth of the tree is always logN or something, so bruteforcing
//it is
//ok nvm this guy is a fucking moron lmao LogN depth my ass. Wrong analysis, wasted 5 minutes. Fuck me
if(Depth[x]<Depth[y]){
swap(x,y);
}
int JumpLevel=Depth[x]-Depth[y];
for(int i=19;i>=0;i--){
if(JumpLevel >> i & 1){
x=Ancestor[x][i];
}
}
for(int i=19;i>=0;i--){
if(Ancestor[x][i]!=Ancestor[y][i]){
x=Ancestor[x][i];
y=Ancestor[y][i];
}
}
x=Par[x];
y=Par[y];
SkipPoint:;
if(Toggle[x]){
return Val[x];
}
/*int cnt=0;
while(!Toggle[Par[x]]&&Par[x]!=500000){
x=Par[x];
}*/
for(int i=19;i>=0;i--){
if(!Toggle[Ancestor[x][i]]){
x=Ancestor[x][i];
}
}
x=Par[x];
if(Toggle[x]&&x!=500000){
return Val[x];
}
return -1;
}
Compilation message
swap.cpp: In function 'int GetRep(int)':
swap.cpp:30:27: error: 'RepU' was not declared in this scope
30 | return CurRep[u]=GetRep[RepU];
| ^~~~
swap.cpp: In function 'void init(int, int, std::vector<int>, std::vector<int>, std::vector<int>)':
swap.cpp:98:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
98 | for(int i=0;i<adj[Cur].size();i++){
| ~^~~~~~~~~~~~~~~~
swap.cpp:111:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
111 | for(int k=0;k<KRTID.size();k++){
| ~^~~~~~~~~~~~~
swap.cpp: In function 'int getMinimumFuelCapacity(int, int)':
swap.cpp:144:2: warning: label 'SkipPoint' defined but not used [-Wunused-label]
144 | SkipPoint:;
| ^~~~~~~~~
