P4377 [USACO18OPEN] Talent Show G

https://www.luogu.com.cn/record/85978845

Luogu/P4377/P4377.cpp

@@ -0,0 +1,56 @@
+#include <iostream>
+#include <algorithm>
+#include <cmath>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 255,
+          W = 1005;
+const double eps = 1e-6;
+
+int n, w, a[N], b[N];
+double f[W];
+
+bool check(double x) {
+    std::fill_n(f + 1, w, -1e9);
+
+    for (int i = 1; i <= n; i++) {
+        for (int j = w; j >= 0; j--) {
+            int k = std::min(w, j + a[i]);
+
+            f[k] = std::max(f[k], f[j] + b[i] - x * a[i]);
+        }
+    }
+
+    return f[w] >= 0;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> w;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i] >> b[i];
+    }
+
+    double l = 0,
+           r = 1e6;
+
+    while (r - l > eps) {
+        double mid = (l + r) / 2;
+
+        if (check(mid)) {
+            l = mid;
+        } else {
+            r = mid;
+        }
+    }
+
+    cout << static_cast<int>(std::floor(l * 1000)) << endl;
+
+    return 0;
+}