一、問題描述
有15個公司和30種產品。
每個公司生產不同種類任意多種產品，每個公司生成產品都會產生一定的費用。
例如：

需要生產6種產品，分別為 1 5 9 10 11 12
6 1 5 9 10 11 12
共有7個公司生產
7
第一家：需要15萬，生成5種產品，1 3 5 7 9
15 5 1 3 5 7 9
第二家...
12 6 2 3 4 6 7 8
第三家...
7 5 3 4 5 6 7
第四家...
16 4 8 9 10 11
第五家...
5 1 2
第六家...
33 12 1 2 3 4 5 6 7 8 9 10 11 12
第七家...
9 3 1 12
 
 13

問：選擇那幾家公司來生產產品，價格最少？

二、程式碼（dfs演算法）

package com.daxiong.day9;

import java.util.Scanner;
import java.io.*;

public class DFSFactory {

    private static int needSize = 30;
    private static int[] needData = new int[needSize];
    private static int facSize = 15;
    private static Factory[] facList = new
 
 Factory[facSize];

    private static int totalCost = 10000;
    private static int[] stack = new int[needSize + 1];
    private static int stackIndex = 1;
    private static int stackFlag = 1;

    public static void main(String[] args) throws Exception {
        readData();
        print();
        System.out.println();
        dfs(0
 
);
    }

    public static void dfs(int index) {

        if (index == facSize) {
            return;
        }

        Factory initFac = facList[index];
        int[] initCates = initFac.categories;
        stack[0] = initFac.cost; // 首位存錢
        for (int i = 0; i < needSize; i++) {
            for (int j = 0; j < initFac.size; j++) {
                if (needData[i] == initCates[j]) {
                    stack[stackIndex] = needData[i];
                    stackIndex++;
                }
            }
        }
        System.out.println("factory:" + index + "," + initFac.cost);
        for (int i = index + 1; i < facSize; i++) {
            Factory factory = facList[i];
            if (isOk(factory, i) == 0 && factory.selected == 0) {
                System.out.println("花費:" + (stack[0] < totalCost ? stack[0] : totalCost)); // 清空當前
                /*System.out.println("stackFlag:" + stackFlag);
                System.out.println("stackIndex:" + stackIndex);*/

                for (int j = stackFlag; j < stackIndex; j++) {
                    stack[j] = 0;
                }
                stack[0] = stack[0] - factory.cost;
                stackIndex = stackFlag;
                factory.selected = 1;
                System.out.println();
            }
        }

        //  清空
        for (int j = 0; j < stackIndex; j++) {
            stack[j] = 0;
        }
        stackIndex = 1;
        stackFlag = 1;
        for (int j = 0; j < facSize; j++) {
            facList[j].selected = 0;
        }
        dfs(index + 1);
    }

    /**
     * @param nextFac
     * @return 0 : 滿足條件！ -1 : 不滿足條件
     */
    public static int isOk(Factory nextFac, int facFlag) {
        stackFlag = stackIndex;
        int[] nextCates = nextFac.categories;
        boolean flagNeed;
        boolean flagNext;
        // 累積類別
        for (int i = 0; i < needSize; i++) {
            flagNeed = false;
            flagNext = false;
            for (int j = 1; j < stackIndex; j++) {
                if (needData[i] == stack[j]) {
                    flagNeed = true;
                }
            }
            // System.out.println("needData[" + i + "]:" + needData[i] +
            // ",flagNeed:" + flagNeed);
            if (!flagNeed) { // 說明沒有
                for (int j = 0; j < nextFac.size; j++) {
                    if (needData[i] == nextCates[j]) {
                        flagNext = true;
                    }
                }
            }
            if (flagNext) {
                stack[stackIndex] = needData[i];
                stackIndex++;
                // System.out.println("stackIndex:" + stackIndex);
            }
        }

        if (stackFlag != stackIndex) { // 有部分
            System.out.println("factory:" + facFlag + "," + nextFac.cost);
            stack[0] = stack[0] + nextFac.cost; // 存錢
        }

        if (stackIndex == (needSize + 1)) {
            return 0;
        } else {
            return -1;
        }
    }

    // 判斷是否滿足條件

    // 讀取資料
    public static void readData() throws Exception {
        // Scanner sc = new Scanner(System.in);
        Scanner sc = new Scanner(new File("src/resource/case.txt"));
        while (true) {
            needSize = sc.nextInt();
            for (int i = 0; i < needSize; i++) {
                needData[i] = sc.nextInt();
            }
            facSize = sc.nextInt();
            for (int i = 0; i < facSize; i++) {
                int cost = sc.nextInt();
                int size = sc.nextInt();
                int[] categories = new int[size];
                for (int j = 0; j < size; j++) {
                    categories[j] = sc.nextInt();
                }
                Factory fac = new Factory(cost, size, categories);
                facList[i] = fac;
            }
            if (sc.nextInt() == 0) {
                sc.close();
                break;
            }
        }
    }

    // 測試資料
    public static void print() {
        for (int i = 0; i < facSize; i++) {
            System.out.print(facList[i].cost + " " + facList[i].size + " ");
            for (int j = 0; j < facList[i].size; j++) {
                System.out.print(facList[i].categories[j] + " ");
            }
            System.out.println();
        }
    }

}

class Factory {
    int cost;
    int size;
    int[] categories;
    int selected;

    public Factory() {

    }

    public Factory(int cost, int size, int[] categories) {
        super();
        this.cost = cost;
        this.size = size;
        this.categories = new int[size];
        this.categories = categories;
        this.selected = 0;
    }
}

測試資料：

6 1 5 9 10 11 12
7
15 5 1 3 5 7 9
12 6 2 3 4 6 7 8
7 5 3 4 5 6 7
16 4 8 9 10 11
5 1 2
33 12 1 2 3 4 5 6 7 8 9 10 11 12
9 3 1 12 13
0