52 lines
1.6 KiB
C#
52 lines
1.6 KiB
C#
/**
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* File: fractional_knapsack.cs
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* Created Time: 2023-07-21
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* Author: hpstory (hpstory1024@163.com)
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*/
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namespace hello_algo.chapter_greedy;
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/* Item */
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class Item(int w, int v) {
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public int w = w; // Item weight
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public int v = v; // Item value
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}
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public class fractional_knapsack {
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/* Fractional knapsack: Greedy */
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double FractionalKnapsack(int[] wgt, int[] val, int cap) {
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// Create an item list, containing two properties: weight, value
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Item[] items = new Item[wgt.Length];
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for (int i = 0; i < wgt.Length; i++) {
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items[i] = new Item(wgt[i], val[i]);
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}
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// Sort by unit value item.v / item.w from high to low
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Array.Sort(items, (x, y) => (y.v / y.w).CompareTo(x.v / x.w));
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// Loop for greedy selection
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double res = 0;
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foreach (Item item in items) {
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if (item.w <= cap) {
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// If the remaining capacity is sufficient, put the entire item into the knapsack
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res += item.v;
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cap -= item.w;
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} else {
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// If the remaining capacity is insufficient, put part of the item into the knapsack
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res += (double)item.v / item.w * cap;
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// No remaining capacity left, thus break the loop
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break;
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}
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}
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return res;
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}
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[Test]
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public void Test() {
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int[] wgt = [10, 20, 30, 40, 50];
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int[] val = [50, 120, 150, 210, 240];
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int cap = 50;
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// Greedy algorithm
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double res = FractionalKnapsack(wgt, val, cap);
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Console.WriteLine("The maximum value within the bag capacity is" + res);
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}
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} |