P2943 [USACO09MAR]Cleaning Up G

https://www.luogu.com.cn/record/77050304

Luogu/P2943/P2943.cpp

@@ -0,0 +1,53 @@
+#include <iostream>
+#include <cmath>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 40005;
+
+int n, m, t, p[N], pre[N], lst[N], nxt[N], pos[N], cnt[N], f[N];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> m;
+
+    std::fill(f, f + 1 + n, 0x3f3f3f3f);
+
+    for (int i = 1; i <= n; i++) {
+        cin >> p[i];
+
+        pre[i] = lst[p[i]];
+        nxt[lst[p[i]]] = i;
+        lst[p[i]] = i;
+        nxt[i] = n + 1;
+    }
+
+    t = std::sqrt(n);
+    f[1] = 1;
+
+    for (int i = 1; i <= t; i++) {
+        pos[i] = 1;
+    }
+
+    for (int i = 1; i <= n; i++) {
+        for (int j = 1; j <= t; j++) {
+            if (pre[i] < pos[j]) cnt[j]++;
+
+            if (cnt[j] > j) {
+                cnt[j]--;
+
+                while (nxt[pos[j]++] < i) {}
+            }
+
+            f[i] = std::min(f[i], f[pos[j] - 1] + (int)std::pow(j, 2));
+        }
+    }
+
+    cout << f[n] << endl;
+
+    return 0;
+}