P3572 [POI2014]PTA-Little Bird

https://www.luogu.com.cn/record/77644318

Luogu/P3572/P3572.cpp

@@ -0,0 +1,46 @@
+#include <iostream>
+#include <deque>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1000005;
+
+int n, q, k, d[N];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> d[i];
+    }
+
+    cin >> q;
+
+    while (q--) {
+        cin >> k;
+
+        std::vector<int> f(n + 1);
+        std::deque<int> q;
+
+        q.push_back(1);
+        for (int i = 2; i <= n; i++) {
+            while (!q.empty() && q.front() < i - k) q.pop_front();
+            f[i] = f[q.front()] + (d[q.front()] <= d[i]);
+            while (!q.empty()
+                   && (f[q.back()] > f[i]
+                       || f[q.back()] == f[i] && d[q.back()] <= d[i]))
+                q.pop_back();
+            q.push_back(i);
+        }
+
+        cout << f[n] << endl;
+    }
+
+    return 0;
+}