#include <bits/stdc++.h>
#define pb push_back
#define f first
#define sc second
using namespace std;
typedef long long int ll;
typedef string str;
struct dsu{
int n;
vector<int> sz, p;
dsu(int nn){
n = nn;
sz.resize(n, 1);
p.resize(n);
for(int i = 0; i < n; i++) p[i] = i;
}
int get(int x){
if(p[x] != x) p[x] = get(p[x]);
return p[x];
}
void unite(int a, int b){
a = get(a), b = get(b);
if(a == b) return;
if(sz[b] > sz[a]) swap(a, b);
sz[a]+=sz[b];
sz[b] = 0;
p[b] = a;
}
};
ll minimum_walk(vector<int> p, int s){
int n = p.size();
ll ans = 0;
vector<int> C(n, -1), sz;
int k = 0;
for(int i = 0; i < n; i++){
if(C[i] != -1) continue;
int x = p[i];
C[i] = k;
sz.pb(1);
ans+=abs(i-x);
while(x != i){
C[x] = k;
sz.back()++;
ans+=abs(p[x]-x);
x = p[x];
}
k++;
}
vector<int> first(k, -1), last(k);
for(int i = 0; i < n; i++){
if(first[C[i]] == -1) first[C[i]] = i;
last[C[i]] = i;
}
vector<bool> unnecessary(k, 0);
for(int i = 0; i < n; i++){
if(sz[C[i]] > 1 || i == s) break;
unnecessary[C[i]] = 1;
}
for(int i = n-1; i >= 0; i--){
if(sz[C[i]] > 1 || i == s) break;
unnecessary[C[i]] = 1;
}
dsu ds(k);
auto cnt = sz;
set<int> st;
for(int i = 0; i < n; i++){
if(unnecessary[C[i]]) continue;
if(!st.empty() && st.find(C[i]) == st.end()){
ds.unite(*st.begin(), C[i]);
}
st.insert(C[i]);
cnt[C[i]]--;
if(cnt[C[i]] == 0) st.erase(C[i]);
}
for(int i = 0; i+1 < n; i++){
if(unnecessary[C[i]] || unnecessary[C[i+1]]) continue;
if(ds.get(C[i]) != ds.get(C[i+1])) ds.unite(C[i], C[i+1]), ans+=2;
}
return ans;
}
Compilation message
/usr/bin/ld: /tmp/ccjHK6F8.o: in function `main':
grader.cpp:(.text.startup+0x98): undefined reference to `find_best(int)'
collect2: error: ld returned 1 exit status
