47 lines
1.3 KiB
JavaScript
47 lines
1.3 KiB
JavaScript
/**
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* File: fractional_knapsack.js
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* Created Time: 2023-09-02
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* Author: Justin (xiefahit@gmail.com)
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*/
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/* Item */
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class Item {
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constructor(w, v) {
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this.w = w; // Item weight
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this.v = v; // Item value
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}
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}
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/* Fractional knapsack: Greedy */
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function fractionalKnapsack(wgt, val, cap) {
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// Create an item list, containing two properties: weight, value
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const items = wgt.map((w, i) => new Item(w, val[i]));
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// Sort by unit value item.v / item.w from high to low
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items.sort((a, b) => b.v / b.w - a.v / a.w);
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// Loop for greedy selection
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let res = 0;
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for (const item of 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 += (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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/* Driver Code */
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const wgt = [10, 20, 30, 40, 50];
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const val = [50, 120, 150, 210, 240];
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const cap = 50;
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const n = wgt.length;
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// Greedy algorithm
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const res = fractionalKnapsack(wgt, val, cap);
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console.log(`不超过背包容量的最大物品价值为 ${res}`);
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