#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define pb emplace_back
#define AI(i) begin(i), end(i)
template<class T> bool chmin(T &a, T b) { return b < a && (a = b, true); }
template<class T> bool chmax(T &a, T b) { return a < b && (a = b, true); }
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void kout() { cerr << endl; }
template<class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ', kout(b...); }
template<class T> void debug(T l, T r) { while (l != r) cerr << *l << " \n"[next(l)==r], ++l; }
#else
#define DE(...) 0
#define debug(...) 0
#endif
const int MAX_N = 300010;
#include "books.h"
long long minimum_walk(std::vector<int> p, int s) {
int n = p.size();
vector<int> cntl(n+1), cntr(n+1);
for (int i = 0;i < n;++i) {
if (p[i] < i)
++cntl[p[i]+1], --cntl[i+1];
if (p[i] > i)
++cntr[i], --cntr[p[i]];
}
if (is_sorted(AI(p))) return 0;
ll res = 0;
for (int i = 1;i <= n;++i) {
cntr[i] += cntr[i-1];
cntl[i] += cntl[i-1];
}
int l = 0, r = n-1;
while (p[l] == l) ++l;
while (p[r] == r) --r;
for (int i = l;i < r;++i) {
res += max({cntl[i+1], cntr[i], 1}) * 2;
}
//
if (s > r) res += (s - r) * 2;
if (s < l) res += (l - s) * 2;
if (s <= r && s >= l) {
int mn = n + n;
int L = R = s;
while (cntl[L]) --L;
while (cntr[R]) ++R;
auto valid = [&](int g) {
if (min(cntl[g], cntr[g]) == 0) return true;
int l = g, r = g, ml = min(g, p[g]), mr = max(g, p[g]);
while (ml < l || mr > r) {
while (ml < l) {
--l;
chmin(ml, p[l]);
chmax(mr, p[l]);
}
while (mr > r) {
++r;
chmin(ml, p[r]);
chmax(mr, p[r]);
}
}
return ml == L && mr == R;
};
for (int i = L;i <= R;++i) {
if (valid(i))
chmin(mn, abs(i-s) * 2);
}
res += mn;
}
return res;
}
Compilation message
books.cpp: In function 'long long int minimum_walk(std::vector<int>, int)':
books.cpp:53:11: error: 'R' was not declared in this scope
53 | int L = R = s;
| ^
