P1880 [NOI1995] 石子合并

R72851962

Luogu/P1880/P1880.cpp

@@ -0,0 +1,48 @@
+#include <cstring>
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 105 << 1;
+
+int n, a[N], sum[N], f1[N][N], f2[N][N], ans1, ans2;
+
+int main() {
+    std::ios::sync_with_stdio(false);
+
+    memset(f1, 0x3f, sizeof(f1));
+    ans1 = 0x3f3f3f3f;
+
+    cin >> n;
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+        a[i + n] = a[i];
+    }
+    for (int i = 1; i < (n << 1); i++) {
+        sum[i] = sum[i - 1] + a[i];
+        f1[i][i] = f2[i][i] = 0;
+    }
+
+    for (int i = 2; i <= n; i++) {
+        for (int l = 1, r = i; r < (n << 1); l++, r++) {
+            for (int k = l; k < r; k++) {
+                f1[l][r] = std::min(f1[l][r], f1[l][k] + f1[k + 1][r]);
+                f2[l][r] = std::max(f2[l][r], f2[l][k] + f2[k + 1][r]);
+            }
+            f1[l][r] += sum[r] - sum[l - 1];
+            f2[l][r] += sum[r] - sum[l - 1];
+        }
+    }
+
+    for (int i = 1; i <= n; i++) {
+        ans1 = std::min(ans1, f1[i][i + n - 1]);
+        ans2 = std::max(ans2, f2[i][i + n - 1]);
+    }
+
+    cout << ans1 << endl
+         << ans2 << endl;
+
+    return 0;
+}