이 제출은 이전 버전의 oj.uz에서 채점하였습니다. 현재는 제출 당시와는 다른 서버에서 채점을 하기 때문에, 다시 제출하면 결과가 달라질 수도 있습니다.
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pll pair<ll,ll>
#define pii pair<int,int>
#define fs first
#define sc second
#define tiii tuple<int,int,int>
#define tlll tuple<ll,ll,ll>
const int mxn = 1e5+10;
vector<int> tree[mxn];
int link_top[mxn],sz[mxn],bs[mxn],idx[mxn],par[mxn],dep[mxn];
int N;
int arr[mxn];
vector<pii> req;
deque<tiii> dq[mxn];
int cnt = 0;
int dfs1(int now){
sz[now] = 1;
for(auto nxt:tree[now]){
par[nxt] = now;
dep[nxt] = dep[now]+1;
sz[now] += dfs1(nxt);
if(!bs[now]||sz[nxt]>sz[bs[now]])bs[now] = nxt;
}
return sz[now];
}
void dfs2(int now,int top){
dq[top].push_back(tiii(dep[now],dep[now],arr[now]));
link_top[now] = top;
idx[now] = ++cnt;
if(bs[now])dfs2(bs[now],top);
for(auto nxt:tree[now]){
if(nxt == bs[now])continue;
dfs2(nxt,nxt);
}
return;
}
struct BIT{
int bit[mxn];
BIT(){
memset(bit,0,sizeof(bit));
}
void modify(int p,int v){
for(;p<mxn;p+=p&-p)bit[p] += v;
return;
}
ll getval(int p){
ll re = 0;
for(;p>0;p-= p&-p)re += bit[p];
return re;
}
};
BIT bit;
ll get_inv(vector<pii> &v){
ll re = 0;
for(auto &i:v){
re += 1ll*i.fs*bit.getval(i.sc-1);
bit.modify(i.sc,i.fs);
}
for(auto &i:v){
bit.modify(i.sc,-(bit.getval(i.sc)-bit.getval(i.sc-1)));
}
return re;
}
void calc(int a,int b){
vector<pii> vv;
int now = a;
//cerr<<"CALC:"<<a<<','<<b<<":"<<endl;
while(now){
vector<pii> v;
int tp = link_top[now];
int st = get<0>(dq[tp].front());
//cerr<<now<<' '<<tp<<":";for(auto &[a,b,c]:dq[tp])cerr<<a<<' '<<b<<' '<<c<<',';
//cerr<<endl;
while(!dq[tp].empty()){
auto &[s,e,val] = dq[tp].front();
if(s>dep[now])break;
v.push_back(pii(min(e,dep[now])-s+1,val));
if(e>dep[now]){
s = dep[now]+1;
break;
}
dq[tp].pop_front();
}
dq[tp].push_front(tiii(st,dep[now],arr[b]));
now = par[tp];
for(auto it = v.rbegin();it != v.rend();it++)vv.push_back(*it);
}
//cerr<<"V:";for(auto [a,b]:vv)cerr<<a<<' '<<b<<',';cerr<<endl;
cout<<get_inv(vv)<<'\n';
return;
}
vector<int> all;
int main(){
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin>>N;
all.push_back(0);
for(int i = 1;i<=N;i++){
cin>>arr[i];
all.push_back(arr[i]);
}
sort(all.begin(),all.end());all.resize(unique(all.begin(),all.end())-all.begin());
for(int i = 1;i<=N;i++){
arr[i] = lower_bound(all.begin(),all.end(),arr[i])-all.begin();
}
for(int i = 1;i<N;i++){
int a,b;
cin>>a>>b;
tree[a].push_back(b);
req.push_back({a,b});
}
dfs1(1);
dfs2(1,1);
for(auto &i:req)calc(i.fs,i.sc);
}
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