Add the initial EN translation for C++ code (#1346)

en/codes/cpp/chapter_greedy/fractional_knapsack.cpp

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+/**
+ * File: fractional_knapsack.cpp
+ * Created Time: 2023-07-20
+ * Author: krahets (krahets@163.com)
+ */
+
+#include "../utils/common.hpp"
+
+/* Item */
+class Item {
+  public:
+    int w; // Item weight
+    int v; // Item value
+
+    Item(int w, int v) : w(w), v(v) {
+    }
+};
+
+/* Fractional knapsack: Greedy */
+double fractionalKnapsack(vector<int> &wgt, vector<int> &val, int cap) {
+    // Create an item list, containing two properties: weight, value
+    vector<Item> items;
+    for (int i = 0; i < wgt.size(); i++) {
+        items.push_back(Item(wgt[i], val[i]));
+    }
+    // Sort by unit value item.v / item.w from high to low
+    sort(items.begin(), items.end(), [](Item &a, Item &b) { return (double)a.v / a.w > (double)b.v / b.w; });
+    // Loop for greedy selection
+    double res = 0;
+    for (auto &item : items) {
+        if (item.w <= cap) {
+            // If the remaining capacity is sufficient, put the entire item into the knapsack
+            res += item.v;
+            cap -= item.w;
+        } else {
+            // If the remaining capacity is insufficient, put part of the item into the knapsack
+            res += (double)item.v / item.w * cap;
+            // No remaining capacity left, thus break the loop
+            break;
+        }
+    }
+    return res;
+}
+
+/* Driver Code */
+int main() {
+    vector<int> wgt = {10, 20, 30, 40, 50};
+    vector<int> val = {50, 120, 150, 210, 240};
+    int cap = 50;
+
+    // Greedy algorithm
+    double res = fractionalKnapsack(wgt, val, cap);
+    cout << "The maximum value within the bag capacity is " << res << endl;
+
+    return 0;
+}