#742. 【IOI1998】Polygon

https://sjzezoj.com/submission/64190

S2OJ/742/742.cpp

@@ -0,0 +1,67 @@
+#include <algorithm>
+#include <iostream>
+#include <limits>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 55 << 1;
+
+int n, w[N], f[N][N], g[N][N], ans;
+char op[N];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+
+    cin >> n;
+    for (int i = 1; i <= n; i++) {
+        cin >> op[i] >> w[i];
+        w[n + i] = w[i];
+        op[n + i] = op[i];
+    }
+
+    for (int i = 1; i <= (n << 1); i++) {
+        f[i][i] = g[i][i] = w[i];
+    }
+    for (int len = 2; len <= n; len++) {
+        for (int l = 1, r = len; r <= n * 2; l++, r++) {
+            f[l][r] = std::numeric_limits<int>::min();
+            g[l][r] = std::numeric_limits<int>::max();
+
+            for (int k = l; k < r; k++) {
+                int maxl = f[l][k], maxr = f[k + 1][r];
+                int minl = g[l][k], minr = g[k + 1][r];
+
+                if (op[k + 1] == 't') {
+                    f[l][r] = std::max(f[l][r], maxl + maxr);
+                    g[l][r] = std::min(g[l][r], minl + minr);
+                } else {
+                    int x1 = minl * minr,
+                        x2 = minl * maxr,
+                        x3 = maxl * minr,
+                        x4 = maxl * maxr;
+                    f[l][r] = std::max({f[l][r], x1, x2, x3, x4});
+                    g[l][r] = std::min({g[l][r], x1, x2, x3, x4});
+                }
+            }
+        }
+    }
+
+    ans = std::numeric_limits<int>::min();
+    for (int i = 1; i <= n; i++) {
+        ans = std::max(ans, f[i][n + i - 1]);
+    }
+
+    cout << ans << endl;
+
+    for (int i = 1; i <= n; i++) {
+        if (ans == f[i][i + n - 1]) {
+            cout << i << ' ';
+        }
+    }
+
+    cout << endl;
+
+    return 0;
+}