// time_limit/solution-o-ans.cpp
#ifndef ATCODER_INTERNAL_BITOP_HPP
#define ATCODER_INTERNAL_BITOP_HPP 1
#ifdef _MSC_VER
#include <intrin.h>
#endif
namespace atcoder {
namespace internal {
// @param n `0 <= n`
// @return minimum non-negative `x` s.t. `n <= 2**x`
int ceil_pow2(int n) {
int x = 0;
while ((1U << x) < (unsigned int)(n)) x++;
return x;
}
// @param n `1 <= n`
// @return minimum non-negative `x` s.t. `(n & (1 << x)) != 0`
constexpr int bsf_constexpr(unsigned int n) {
int x = 0;
while (!(n & (1 << x))) x++;
return x;
}
// @param n `1 <= n`
// @return minimum non-negative `x` s.t. `(n & (1 << x)) != 0`
int bsf(unsigned int n) {
#ifdef _MSC_VER
unsigned long index;
_BitScanForward(&index, n);
return index;
#else
return __builtin_ctz(n);
#endif
}
} // namespace internal
} // namespace atcoder
#endif // ATCODER_INTERNAL_BITOP_HPP
#ifndef ATCODER_SEGTREE_HPP
#define ATCODER_SEGTREE_HPP 1
#include <algorithm>
#include <cassert>
#include <vector>
namespace atcoder {
template <class S, S (*op)(S, S), S (*e)()> struct segtree {
public:
segtree() : segtree(0) {}
explicit segtree(int n) : segtree(std::vector<S>(n, e())) {}
explicit segtree(const std::vector<S>& v) : _n(int(v.size())) {
log = internal::ceil_pow2(_n);
size = 1 << log;
d = std::vector<S>(2 * size, e());
for (int i = 0; i < _n; i++) d[size + i] = v[i];
for (int i = size - 1; i >= 1; i--) {
update(i);
}
}
void set(int p, S x) {
assert(0 <= p && p < _n);
p += size;
d[p] = x;
for (int i = 1; i <= log; i++) update(p >> i);
}
S get(int p) const {
assert(0 <= p && p < _n);
return d[p + size];
}
S prod(int l, int r) const {
assert(0 <= l && l <= r && r <= _n);
S sml = e(), smr = e();
l += size;
r += size;
while (l < r) {
if (l & 1) sml = op(sml, d[l++]);
if (r & 1) smr = op(d[--r], smr);
l >>= 1;
r >>= 1;
}
return op(sml, smr);
}
S all_prod() const { return d[1]; }
template <bool (*f)(S)> int max_right(int l) const {
return max_right(l, [](S x) { return f(x); });
}
template <class F> int max_right(int l, F f) const {
assert(0 <= l && l <= _n);
assert(f(e()));
if (l == _n) return _n;
l += size;
S sm = e();
do {
while (l % 2 == 0) l >>= 1;
if (!f(op(sm, d[l]))) {
while (l < size) {
l = (2 * l);
if (f(op(sm, d[l]))) {
sm = op(sm, d[l]);
l++;
}
}
return l - size;
}
sm = op(sm, d[l]);
l++;
} while ((l & -l) != l);
return _n;
}
template <bool (*f)(S)> int min_left(int r) const {
return min_left(r, [](S x) { return f(x); });
}
template <class F> int min_left(int r, F f) const {
assert(0 <= r && r <= _n);
assert(f(e()));
if (r == 0) return 0;
r += size;
S sm = e();
do {
r--;
while (r > 1 && (r % 2)) r >>= 1;
if (!f(op(d[r], sm))) {
while (r < size) {
r = (2 * r + 1);
if (f(op(d[r], sm))) {
sm = op(d[r], sm);
r--;
}
}
return r + 1 - size;
}
sm = op(d[r], sm);
} while ((r & -r) != r);
return 0;
}
private:
int _n, size, log;
std::vector<S> d;
void update(int k) { d[k] = op(d[2 * k], d[2 * k + 1]); }
};
} // namespace atcoder
#endif // ATCODER_SEGTREE_HPP
#include "towers.h"
#include <bits/stdc++.h>
using namespace std;
struct Node {
int max;
int min;
int max_right_min_left;
int max_left_min_right;
};
typedef optional<Node> OptionalNode;
OptionalNode Empty() {
return {};
}
OptionalNode Merge(OptionalNode l, OptionalNode r) {
if (!l.has_value()) {
return r;
}
if (!r.has_value()) {
return l;
}
return (Node) {
max(l.value().max, r.value().max),
min(l.value().min, r.value().min),
max(max(l.value().max_right_min_left, r.value().max_right_min_left),
r.value().max - l.value().min),
max(max(l.value().max_left_min_right, r.value().max_left_min_right),
l.value().max - r.value().min)
};
}
typedef atcoder::segtree<OptionalNode, Merge, Empty> Segtree;
int N;
vector<int> H;
Segtree st;
void init(int _N, std::vector<int> _H) {
N = _N;
H = _H;
st = Segtree(N);
for (int i = 0; i < N; ++i) {
st.set(i, (Node) {H[i], H[i], INT_MIN, INT_MIN});
}
}
int max_towers(int L, int R, int D) {
int answer = 1;
int now = L;
for (bool up = true; now < R; up = !up) {
if (up) {
int min_tall = st.max_right(now, [&] (OptionalNode node) {
return !node.has_value() || node.value().max_right_min_left < D;
});
if (min_tall <= R) {
now = min_tall;
} else {
now = R;
}
} else {
int min_choose = st.max_right(now, [&] (OptionalNode node) {
return !node.has_value() || node.value().max_left_min_right < D;
});
if (min_choose <= R) {
now = min_choose;
++answer;
} else {
now = R;
}
}
}
return answer;
}
