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;
int main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
int N, D; cin >> N >> D;
vector<int> A(N); for (int &a : A) cin >> a;
vector<int> ord(N); iota(ord.begin(), ord.end(), 0);
sort(ord.begin(), ord.end(), [&](const int &i, const int &j) {
return make_pair(A[i], -i) < make_pair(A[j], -j);
});
int S = 1;
while (S < N) S *= 2;
vector<int> loc(N);
for (int i = 0; i < N; ++i) loc[ord[i]] = i;
struct Node {
int best = 0;
int pref = 0;
int suff = 0;
bool all = false;
};
auto merge = [&](Node l, Node r) {
Node ans;
ans.all = l.all & r.all;
ans.best = max({l.best, r.best, l.suff + r.suff});
ans.pref = l.all ? l.pref + r.pref : l.pref;
ans.suff = r.all ? r.suff + l.suff : r.suff;
return ans;
};
vector<Node> tree0(2 * S);
auto modify0 = [&](int p) {
tree0[p += S] = {1, 1, 1, true};
p /= 2;
while (p > 0) {
tree0[p] = merge(tree0[2 * p], tree0[2 * p + 1]);
p /= 2;
}
};
auto query0 = [&](int l, int r) {
Node ansl{};
Node ansr{};
for (l += S, r += S; l <= r; l /= 2, r /= 2) {
if (l % 2) ansl = merge(ansl, tree0[l++]);
if (r % 2 == 0) ansr = merge(tree0[r--], ansr);
}
return merge(ansl, ansr).best;
};
vector<vector<int>> evts(N);
reverse(ord.begin(), ord.end());
for (int i : ord) {
int lo = i, hi = N - 1;
while (lo < hi) {
int mi = (lo + hi) / 2;
if (query0(i, mi) <= D) hi = mi;
else lo = mi + 1;
}
if (lo + 1 < N) {
evts[lo + 1].push_back(i);
}
modify0(i);
}
vector<int> tree1(2 * S);
auto modify1 = [&](int p, int v) {
tree1[p += S] = v;
p /= 2;
while (p > 0) {
tree1[p] = max(tree1[2 * p], tree1[2 * p + 1]);
p /= 2;
}
};
auto query1 = [&](int l, int r) {
int ans = 0;
for (l += S, r += S; l <= r; l /= 2, r /= 2) {
if (l % 2) ans = max(ans, tree1[l++]);
if (r % 2 == 0) ans = max(ans, tree1[r--]);
}
return ans;
};
int ans = 0;
for (int i = 0; i < N; ++i) {
int dp = query1(0, loc[i]) + 1;
ans = max(ans, dp);
modify1(loc[i], dp);
for (int j : evts[i]) {
modify1(loc[j], 0);
}
}
cout << ans << '\n';
return 0;
}
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