#include "bits/stdc++.h"
using namespace std;
#define ORD_SET
// #define ROPE
#ifdef ORD_SET
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#endif
#ifdef ROPE
#include <ext/rope>
using namespace __gnu_cxx;
#endif
// #pragma comment(linker, "/stack:200000000")
// #pragma GCC optimize("Ofast")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
using ll = long long;
using ld = long double;
#define pb push_back
#define ff first
#define ss second
#define sz(x) (ll)(x).size()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
void freopen(string s) { freopen((s+".in").c_str(), "r", stdin); freopen((s+".out").c_str(), "w", stdout); }
void ioigold2024insh() { ios_base::sync_with_stdio(false); cin.tie(NULL); }
void pre(ll a) { cout<<fixed<<setprecision(a); }
ll bit(ll a) { return __builtin_popcountll(a); }
ll binmul(ll a, ll b, ll c) { ll res = 0; while(b) { if(b&1) (res += a) %= c; (a += a) %= c; b >>= 1; } return res; }
ll binpow(ll a, ll b, ll c) { ll res = 1; while(b) { if(b&1) (res *= a) %= c; (a *= a) %= c; b >>= 1; } return res; }
template<typename T> T gcd(T a, T b) { if(b==0) return a; return gcd(b, a%b); }
template<typename T> T lcm(T a, T b) { return a/gcd(a, b)*b; }
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ld rnd() { return rng()%INT_MAX*1.0/INT_MAX; }
struct sn { ll l, r, x; };
const ll mod = 1e9+7, inf = 1e18+7, MX = LLONG_MAX, MN = LLONG_MIN;
const ll N = 4e5+5;
vector<ll> g[N];
ordered_set<ll> st[N], ts[N];
ll n, res[N], head[N];
void input(ll p) {
ll x; cin>>x;
if(!x) {
x = ++n;
g[x].pb(p), g[p].pb(x);
input(x), input(x);
}
else g[p].pb(x), g[x].pb(p);
}
void dfs(ll v, ll p) {
if(v<=n) {
st[root[v]].insert(v), ts[root[v]].insert(-v);
return;
}
ll x = 0, y = 0;
for(auto to: g[v]) {
if(to==p) continue;
dfs(to, v);
res[v] += res[to];
if(!x) x = to;
else y = to;
}
ll res1 = 0, res2 = 0;
x = head[x], y = head[y];
if(sz(st[x])<sz(st[y])) {
for(auto num: st[x]) {
ll s1 = st[y].order_of_key(num);
res1 += s1;
ll s2 = ts[y].order_of_key(-num);
res2 += s2;
}
}
else {
for(auto num: st[y]) {
ll s2 = st[x].order_of_key(num);
res2 += s2;
ll s1 = ts[x].order_of_key(-num);
res1 += s1;
}
}
res[v] += min(res1, res2);
for(auto to: g[v]) {
if(to==p) continue;
if(sz(st[head[to]])>sz(st[head[v]])) swap(head[v], head[to]);
for(auto num: st[head[to]]) st[head[v]].insert(num);
for(auto num: ts[head[to]]) ts[head[v]].insert(num);
}
}
void kigash() {
cin>>n;
ll n1 = n;
input(0);
for(ll i=0; i<N; i++) head[i] = i;
n = n1;
dfs(n+1, 0);
cout<<res[n+1]<<"\n";
return;
}
signed main(/*Kigash Amir*/) {
// freopen("");
ioigold2024insh();
ll tt = 1;
// cin>>tt;
for(ll i=1; i<=tt; i++) kigash();
exit(0);
}
Compilation message
rot.cpp: In function 'void dfs(ll, ll)':
rot.cpp:61:12: error: 'root' was not declared in this scope
61 | st[root[v]].insert(v), ts[root[v]].insert(-v);
| ^~~~
rot.cpp: In function 'void freopen(std::string)':
rot.cpp:31:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
31 | void freopen(string s) { freopen((s+".in").c_str(), "r", stdin); freopen((s+".out").c_str(), "w", stdout); }
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
rot.cpp:31:73: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
31 | void freopen(string s) { freopen((s+".in").c_str(), "r", stdin); freopen((s+".out").c_str(), "w", stdout); }
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
