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 <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr int INF = numeric_limits<int>::max() / 2;
constexpr ll INFLL = numeric_limits<ll>::max() / 2;
template<class T>
istream &operator>>(istream &is, vector<T> &a) {
for (auto &i : a) {
is >> i;
}
return is;
}
struct SegTree {
struct Node {
int mn = INF, mnpos = -1;
int mxdp = -INF;
int push = -1;
Node() = default;
Node(int ri, int i, int dp) {
mn = ri;
mnpos = i;
mxdp = dp;
}
};
Node pull(const Node &a, const Node &b) {
Node ans;
ans.mxdp = max(a.mxdp, b.mxdp);
ans.mn = min(a.mn, b.mn);
if (a.mn < b.mn) {
ans.mnpos = a.mnpos;
} else {
ans.mnpos = b.mnpos;
}
return ans;
}
vector<Node> tree;
int n;
void push(int v, int l, int r) {
if (tree[v].push == -1) {
return;
}
if (l + 1 < r) {
tree[2 * v + 1].push = tree[v].push;
tree[2 * v + 2].push = tree[v].push;
}
tree[v].mn = tree[v].push;
tree[v].push = -1;
}
void build(int v, int l, int r) {
if (l + 1 == r) {
tree[v].mnpos = l;
return;
}
int m = (l + r) / 2;
build(2 * v + 1, l, m);
build(2 * v + 2, m, r);
tree[v] = pull(tree[2 * v + 1], tree[2 * v + 2]);
}
SegTree(int n) : n(n) {
tree.resize(4 * n);
build(0, 0, n);
}
Node get(int v, int l, int r, int li, int ri) {
push(v, l, r);
if (li >= r || l >= ri) {
return {};
}
if (li <= l && r <= ri) {
return tree[v];
}
int m = (l + r) / 2;
return pull(get(2 * v + 1, l, m, li, ri), get(2 * v + 2, m, r, li, ri));
}
Node get(int li, int ri) {
return get(0, 0, n, li, ri);
}
void update(int v, int l, int r, int i, const Node &x) {
push(v, l, r);
if (i < l || i >= r) {
return;
}
if (l + 1 == r) {
tree[v] = x;
return;
}
int m = (l + r) / 2;
update(2 * v + 1, l, m, i, x);
update(2 * v + 2, m, r, i, x);
tree[v] = pull(tree[2 * v + 1], tree[2 * v + 2]);
}
void update(int i, const Node &x) {
update(0, 0, n, i, x);
}
void update_seg(int v, int l, int r, int li, int ri, int x) {
push(v, l, r);
if (li >= r || l >= ri) {
return;
}
if (li <= l && r <= ri) {
tree[v].push = x;
push(v, l, r);
return;
}
int m = (l + r) / 2;
update_seg(2 * v + 1, l, m, li, ri, x);
update_seg(2 * v + 2, m, r, li, ri, x);
tree[v] = pull(tree[2 * v + 1], tree[2 * v + 2]);
}
void update_seg(int li, int ri, int x) {
update_seg(0, 0, n, li, ri, x);
}
};
int main() {
cin.tie(0)->sync_with_stdio(0);
#ifdef __APPLE__
freopen("input.txt", "r", stdin);
#endif
int n, d;
cin >> n >> d;
vector<int> a(n);
cin >> a;
vector<pair<int, int>> coords;
for (int i = 0; i < n; ++i) {
coords.push_back({a[i], i});
}
sort(coords.begin(), coords.end());
// for (int i = 0; i < n; ++i) {
// a[i] = lower_bound(coords.begin(), coords.end(), pair(a[i], i)) - coords.begin();
// }
vector<int> dp(n), ri(n);
SegTree st(n);
for (int i = 0; i < n; ++i) {
dp[i] = 1;
ri[i] = i;
while (1) {
auto cur = st.get(0, n);
if (i - cur.mn <= d) {
break;
}
st.update(cur.mnpos, {INF, cur.mnpos, -INF});
}
{
int it = lower_bound(coords.begin(), coords.end(), pair(a[i], 0)) - coords.begin();
auto cur = st.get(0, it);
dp[i] = max(dp[i], cur.mxdp + 1);
}
{
int it = lower_bound(coords.begin(), coords.end(), pair(a[i], i)) - coords.begin();
st.update(it, {i, it, dp[i]});
}
{
int it = upper_bound(coords.begin(), coords.end(), pair(a[i], INF)) - coords.begin();
st.update_seg(it, n, i);
}
// for (int j = 0; j < i; ++j) {
// if (i - ri[j] <= d && a[j] < a[i]) {
// dp[i] = max(dp[i], dp[j] + 1);
// }
// }
// for (int j = 0; j <= i; ++j) {
// if (i - ri[j] <= d && a[j] >= a[i]) {
// ri[j] = i;
// }
// }
}
for (int i = 0; i < n; ++i) {
ri[i] = st.get(i, i + 1).mn;
}
int ans = 0;
for (int i = 0; i < n; ++i) {
if (ri[i] == n - 1) {
ans = max(ans, dp[i]);
}
}
cout << ans << "\n";
}
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