이 제출은 이전 버전의 oj.uz에서 채점하였습니다. 현재는 제출 당시와는 다른 서버에서 채점을 하기 때문에, 다시 제출하면 결과가 달라질 수도 있습니다.
#include<bits/stdc++.h>
#pragma GCC optimize("O2")
using namespace std;
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define sz(x) (int)x.size()
//#define endl '\n'
int n, d;
const int N = 3e5 + 5;
const int L = (1 << 19);
int a[N];
int mini[N];
int dp[N];
set<pair<int, int>> seg[(L << 1)];
void addto(set<pair<int, int>> &s, pair<int, int> now) {
s.insert(now);
auto it = s.find(now);
if (next(it) != s.end()) {
if (it->se >= next(it)->se) {
s.erase(it);
return;
}
}
while (s.find(now) != s.begin()) {
auto it = s.find(now);
if (it == s.end()) {
throw;
}
if (prev(it)->se < it->se) {
break;
}
s.erase(prev(it));
}
}
int best(set<pair<int, int>> &s, int a) {
auto it = s.lower_bound(mp(a + 1, -(n + 1)));
if (it == s.end()) {
return 0;
}
return it->se;
}
void upd(int ind) {
pair<int, int> now = mp(a[ind], -dp[ind]);
ind += L;
while (ind) {
addto(seg[ind], now);
ind >>= 1;
}
}
int get(int e, int a) {
e++;
e += L;
int ans = 0;
while (e) {
if (e & 1) {
e--;
ans = min(ans, best(seg[e], a));
}
e >>= 1;
}
return ans;
}
void input() {
cin >> n >> d;
for (int i = 1; i <= n; i++) {
cin >> a[i];
}
}
void cremini() {
deque<int> dq;
for (int i = 1; i < d; i++) {
while (!dq.empty()) {
if (a[dq.front()] < a[i]) {
break;
}
dq.pop_front();
}
dq.push_front(i);
}
for (int i = d; i <= n; i++) {
while (!dq.empty()) {
if (a[dq.front()] < a[i]) {
break;
}
dq.pop_front();
}
dq.push_front(i);
if (dq.back() == i - d) {
dq.pop_back();
}
mini[i] = a[dq.back()];
}
for (int i = d; i <= n; i++) {
int tri = a[i];
for (int j = i - d + 1; j <= i; j++) {
tri = min(tri, a[j]);
}
if (tri != mini[i]) {
throw;
}
}
}
void solve() {
cremini();
vector<int> obs;
for (int i = n; i >= 1; i--) {
int lobs = sz(obs), robs = -1;
while (lobs - 1 != robs) {
int m = (lobs + robs + 1) / 2;
if (mini[obs[m]] > a[i]) {
robs = m;
}
else {
lobs = m;
}
}
int limi = n;
if (robs != -1) {
limi = obs[robs];
}
dp[i] = -get(limi, a[i]) + 1;
upd(i);
if (i + d - 1 <= n) {
while (!obs.empty()) {
if (mini[i + d - 1] < mini[obs.back()]) {
break;
}
obs.pop_back();
}
obs.pb(i + d - 1);
}
}
int ans = 0;
for (int i = 1; i <= n; i++) {
ans = max(ans, dp[i]);
}
cout << ans;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
input();
solve();
return 0;
}
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