P2964 [USACO09NOV]A Coin Game S

https://www.luogu.com.cn/record/77095873

Luogu/P2964/P2964.cpp

@@ -0,0 +1,43 @@
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 2005;
+
+// f[当前位置][上一组长度]
+int n, a[N], s[N], f[N][N];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+    }
+
+    for (int i = n; i; i--) {
+        s[i] = s[i + 1] + a[i];
+    }
+
+    for (int i = n; i; i--) {
+        for (int j = 1, k = 1; j <= n; j++, k += 2) {
+            f[i][j] = f[i][j - 1];
+
+            if (k <= n - i + 1) {
+                f[i][j] = std::max(f[i][j], s[i] - f[i + k][k]);
+            }
+
+            if (k + 1 <= n - i + 1) {
+                f[i][j] = std::max(f[i][j], s[i] - f[i + k + 1][k + 1]);
+            }
+        }
+    }
+
+    cout << f[1][1] << endl;
+
+    return 0;
+}