This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include "books.h"
#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define rep2(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define rrep(i, n) for (int i = (int)(n) - 1; i >= 0; --i)
#define rrep2(i, a, b) for (int i = (int)(b) - 1; i >= (int)(a); --i)
#define all(v) begin(v), end(v)
#define rall(v) rbegin(v), rend(v)
using namespace std;
using ll = long long;
constexpr ll inf = 1e18;
template<class T, class U> bool chmin(T& a, const U& b) { return a > b ? a = b, true : false; }
template<class T, class U> bool chmax(T& a, const U& b) { return a < b ? a = b, true : false; }
template<class M>
class SparseTable {
using T = typename M::T;
int n;
vector<vector<T>> dat;
public:
SparseTable(vector<T> a) {
n = a.size();
int h = __lg(n + 1) + 1;
dat.assign(h + 1, vector<T>(n, M::id()));
rep (i, n) dat[0][i] = a[i];
rep (i, h) rep (j, n - (1 << i)) {
dat[i + 1][j] = M::op(dat[i][j], dat[i][j + (1 << i)]);
}
}
T prod(int l, int r) const {
assert(0 <= l && l <= r && r <= n);
int b = __lg(r - l);
return M::op(dat[b][l], dat[b][r - (1 << b)]);
}
template<class F> int max_right(int l, F f) const {
assert(0 <= l && l <= n);
assert(f(M::id()));
if (l == n) return n;
int ok = l, ng = n + 1;
while (ng - ok > 1) {
int m = (ok + ng) / 2;
(f(prod(l, m)) ? ok : ng) = m;
}
return ok;
}
template<class F> int min_left(int r, F f) const {
assert(0 <= r && r <= n);
assert(f(M::id()));
if (r == 0) return 0;
int ok = r, ng = -1;
while (ok - ng > 1) {
int m = (ok + ng) / 2;
(f(prod(m, r)) ? ok : ng) = m;
}
return ok;
}
};
template<class M>
class SegmentTree {
using T = typename M::T;
int n;
vector<T> dat;
public:
SegmentTree(vector<T> a) {
n = 1;
while (n < a.size()) n <<= 1;
dat.assign(n << 1, M::id());
rep (i, a.size()) dat[i + n] = a[i];
for (int i = n - 1; i >= 1; --i) {
dat[i] = M::op(dat[i << 1], dat[i << 1 | 1]);
}
}
T prod(int l, int r) const {
assert(0 <= l && l <= r && r <= n);
T res1 = M::id(), res2 = M::id();
for (l += n, r += n; l < r; l >>= 1, r >>= 1) {
if (l & 1) res1 = M::op(res1, dat[l++]);
if (r & 1) res2 = M::op(dat[--r], res2);
}
return M::op(res1, res2);
}
void set(int k, T x) {
k += n;
dat[k] = x;
while (k > 1) {
k /= 2;
dat[k] = M::op(dat[k << 1], dat[k << 1 | 1]);
}
}
};
struct Min {
using T = ll;
static T op(T a, T b) { return min(a, b); }
static T id() { return inf; }
};
struct Max {
using T = ll;
static T op(T a, T b) { return max(a, b); }
static T id() { return -inf; }
};
long long minimum_walk(std::vector<int> p, int s) {
int n = p.size();
if (is_sorted(all(p))) return 0;
ll ans = 0;
{
while (p.back() == n - 1) {
if (s == n - 1) {
--s;
ans += 2;
}
p.pop_back();
--n;
}
reverse(all(p));
rep (i, n) p[i] = n - 1 - p[i];
s = n - 1 - s;
while (p.back() == n - 1) {
if (s == n - 1) {
--s;
ans += 2;
}
p.pop_back();
--n;
}
reverse(all(p));
rep (i, n) p[i] = n - 1 - p[i];
s = n - 1 - s;
}
rep (i, n) ans += abs(p[i] - i);
vector<ll> mns(n), mxs(n);
{
vector<bool> seen(n);
rep (i, n) {
if (seen[i]) continue;
int j = i;
int mx = 0;
do {
seen[j] = true;
chmax(mx, j);
j = p[j];
} while (i != j);
j = i;
do {
mns[j] = i;
mxs[j] = mx;
j = p[j];
} while (i != j);
}
}
{
vector<bool> seen(n, false);
SegmentTree<Min> seg1(mns);
SegmentTree<Max> seg2(mxs);
rep (i, n) {
if (seen[i]) continue;
int l = mns[i], r = mxs[i];
while (1) {
int l2 = seg1.prod(l, r + 1);
int r2 = seg2.prod(l, r + 1);
if (l == l2 && r == r2) break;
l = l2; r = r2;
}
int j = i;
do {
seen[j] = true;
mns[j] = l;
mxs[j] = r;
seg1.set(j, l);
seg2.set(j, r);
j = p[j];
} while (i != j);
}
}
SparseTable<Min> st1(mns);
SparseTable<Max> st2(mxs);
// rep (i, n) cout << mns[i] << " \n"[i == n - 1];
// rep (i, n) cout << mxs[i] << " \n"[i == n - 1];
// cout << ans << endl;
int l = mns[s], r = mxs[s];
while (l != 0 || r != n - 1) {
int l2 = st2.min_left(l, [&](ll x) { return x <= r; });
int r2 = st1.max_right(r + 1, [&](ll x) { return x >= l; }) - 1;
if (l2 == 0 && l != 0) {
ans += 2;
l = mns[l - 1];
}
else if (r2 == n - 1 && r != n - 1) {
ans += 2;
r = mxs[r + 1];
}
else {
int cnt1 = 0, cnt2 = 0;
while (l > l2) {
++cnt1;
l = mns[l - 1];
}
while (r < r2) {
++cnt2;
r = mxs[r + 1];
}
ans += (min(cnt1, cnt2) + 1) * 2;
l = mns[max<int>(l2 - 1, 0)];
r = mxs[min<int>(r2 + 1, n - 1)];
}
}
return ans;
}
Compilation message (stderr)
books.cpp: In instantiation of 'SegmentTree<M>::SegmentTree(std::vector<typename M::T>) [with M = Min; typename M::T = long long int]':
books.cpp:163:34: required from here
books.cpp:75:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
75 | while (n < a.size()) n <<= 1;
| ~~^~~~~~~~~~
books.cpp: In instantiation of 'SegmentTree<M>::SegmentTree(std::vector<typename M::T>) [with M = Max; typename M::T = long long int]':
books.cpp:164:34: required from here
books.cpp:75:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
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