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47 lines
1.3 KiB
47 lines
1.3 KiB
/**
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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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/* 物品 */
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class Item {
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constructor(w, v) {
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this.w = w; // 物品重量
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this.v = v; // 物品价值
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}
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}
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/* 分数背包：贪心 */
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function fractionalKnapsack(wgt, val, cap) {
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// 创建物品列表，包含两个属性：重量、价值
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const items = wgt.map((w, i) => new Item(w, val[i]));
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// 按照单位价值 item.v / item.w 从高到低进行排序
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items.sort((a, b) => b.v / b.w - a.v / a.w);
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// 循环贪心选择
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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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// 若剩余容量充足，则将当前物品整个装进背包
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res += item.v;
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cap -= item.w;
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} else {
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// 若剩余容量不足，则将当前物品的一部分装进背包
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res += (item.v / item.w) * cap;
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// 已无剩余容量，因此跳出循环
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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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// 贪心算法
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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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