CF1681F Unique Occurrences 题解

include <bits/stdc++.h>

using namespace std;

define ll long long

const int N=5e5+10;
int p[N],siz[N];

define ls (u<<1)

define rs (u<<1|1)

define mid ((l+r)>>1)

struct Edge{
int x,y;
};
stack stk;
ll ans=0,n;
int a[N],b[N],w[N];
vector tr[N<<2];
vector e[N];//每个权值的所有边

int find(int x){
return p[x]==x?x:find(p[x]);
}

void unite(int x,int y){
int fx=find(x),fy=find(y);
if(fx^fy){
if(siz[fy]>siz[fx]) swap(fx,fy);
siz[fx]+=siz[fy];
p[fy]=fx;
stk.push({fx,fy});
}
}

void insert(int u,int l,int r,int jl,int jr,int i){
if(l>jr||r<jl) return ;
if(jl<=l&&r<=jr) return tr[u].push_back(i);
insert(ls,l,mid,jl,jr,i);
insert(rs,mid+1,r,jl,jr,i);
}

void solve(int u,int l,int r){
int now=stk.size();
for(int i:tr[u]){
unite(a[i],b[i]);
}
if(l==r){
for(auto [x,y]:e[l]){
int fx=find(x),fy=find(y);
ans+=1llsiz[fx]siz[fy];
}
}else{
solve(ls,l,mid);
solve(rs,mid+1,r);
}
while(stk.size()>now){
auto [x,y]=stk.top();
stk.pop();
siz[x]-=siz[y];
p[y]=y;
}
}

int main(){
ios::sync_with_stdio(0);
cin.tie(0),cout.tie(0);

cin>>n;
for(int i=1;i<=n;i++) p[i]=i,siz[i]=1;
for(int i=1;i<=n;i++){
cin>>a[i]>>b[i]>>w[i];
e[w[i]].push_back({a[i],b[i]});
insert(1,1,n,1,w[i]-1,i);
insert(1,1,n,w[i]+1,n,i);
}
solve(1,1,n);
cout<<ans;
return 0;
}