设某一机器由n个部件组成,部件编号为1~n,每一种部件都可以从m个供应商处购得。供应商编号为1~m。设w是从供应商j处购得的部件i的重量,c是相应的价格。对于给定的机器部件重量和机器部件价格,计算总价格不超过 cost 的最小重量机器设计,可以在同一个供应商处购得多个部件。要求用JAVA代码使用分枝限界法完成

以下是使用分枝限界法求解最小重量机器设计的JAVA代码：

import java.util.*;

public class MachineDesign {
    
    static class Part {
        int id;
        int[] suppliers;
        int[] prices;
        int[] weights;
        
        public Part(int id, int[] suppliers, int[] prices, int[] weights) {
            this.id = id;
            this.suppliers = suppliers;
            this.prices = prices;
            this.weights = weights;
        }
    }
    
    static class Node implements Comparable<Node> {
        int index;
        int cost;
        int weight;
        int[] selectedSuppliers;
        
        public Node(int index, int cost, int weight, int[] selectedSuppliers) {
            this.index = index;
            this.cost = cost;
            this.weight = weight;
            this.selectedSuppliers = selectedSuppliers.clone();
        }
        
        @Override
        public int compareTo(Node other) {
            return Integer.compare(this.cost, other.cost);
        }
    }
    
    static int n; // number of parts
    static int m; // number of suppliers
    static int costLimit;
    static Part[] parts;
    static int bestWeight;
    static int[] bestSelectedSuppliers;
    
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        
        // read input
        n = scanner.nextInt();
        m = scanner.nextInt();
        costLimit = scanner.nextInt();
        parts = new Part[n];
        for (int i = 0; i < n; i++) {
            int numSuppliers = scanner.nextInt();
            int[] suppliers = new int[numSuppliers];
            int[] prices = new int[numSuppliers];
            int[] weights = new int[numSuppliers];
            for (int j = 0; j < numSuppliers; j++) {
                suppliers[j] = scanner.nextInt();
                prices[j] = scanner.nextInt();
                weights[j] = scanner.nextInt();
            }
            parts[i] = new Part(i + 1, suppliers, prices, weights);
        }
        
        // initialize
        bestWeight = Integer.MAX_VALUE;
        bestSelectedSuppliers = new int[n];
        Arrays.fill(bestSelectedSuppliers, -1);
        
        // solve
        PriorityQueue<Node> queue = new PriorityQueue<>();
        queue.offer(new Node(0, 0, 0, new int[m]));
        while (!queue.isEmpty()) {
            Node node = queue.poll();
            if (node.cost > costLimit) {
                continue;
            }
            if (node.index == n) {
                if (node.weight < bestWeight) {
                    bestWeight = node.weight;
                    bestSelectedSuppliers = node.selectedSuppliers;
                }
                continue;
            }
            Part part = parts[node.index];
            for (int i = 0; i < part.suppliers.length; i++) {
                int supplier = part.suppliers[i] - 1;
                int price = part.prices[i];
                int weight = part.weights[i];
                int[] selectedSuppliers = node.selectedSuppliers.clone();
                selectedSuppliers[supplier]++;
                queue.offer(new Node(node.index + 1, node.cost + price, node.weight + weight, selectedSuppliers));
            }
        }
        
        // output
        System.out.println(bestWeight);
        for (int i = 0; i < n; i++) {
            System.out.print(bestSelectedSuppliers[i] + " ");
        }
    }
}

输入格式为：

n m costLimit
numSuppliers1 supplier11 price11 weight11 supplier12 price12 weight12 ...
numSuppliers2 supplier21 price21 weight21 supplier22 price22 weight22 ...
...

其中 `n` 表示机器部件数，`m` 表示供应商数，`costLimit` 表示价格限制。接下来的 `n` 行每行表示一个部件的信息，包括供应商数、每个供应商的编号、价格和重量。

输出格式为：

bestWeight
selectedSupplier1 selectedSupplier2 ...

其中 `bestWeight` 表示最小重量，`selectedSupplier` 表示每个部件选择的供应商编号。