大神，能帮我看这修改一下吗？

package test;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class MySolution5 {

        private static List<List<Integer[]>> helper(List<Integer[]> bookSet, int num) {

                List<List<Integer[]>> ret = new ArrayList<>();
                List<Integer[]> bookSetCombination = new ArrayList<>();

                if (num > bookSet.size())
                        return ret;

                if (num == 1) {
                        for (Integer[] book : bookSet) {
                                bookSetCombination.add(book.clone());
                                ret.add(bookSetCombination);
                        }
                        return ret;
                }

                if (num == bookSet.size()) {
                        for (Integer[] book : bookSet) {
                                bookSetCombination.add(book.clone());
                        }
                        ret.add(bookSetCombination);
                        return ret;
                }

                if (num < bookSet.size()) {

                        List<Integer[]> tmpBookSet = new ArrayList<>(bookSet);
                        for (int i = 0; i < bookSet.size(); i++) {
                                bookSetCombination.add(bookSet.get(i).clone());
                                //注释掉这句，是可以运行的
                                ret = helper(tmpBookSet, num - 1);
                                for (List<Integer[]> combination : ret) {
                                        bookSetCombination.addAll(combination);
                                        ret.add(bookSetCombination);
                                }
                        }
                }
                return ret;
        }

        public static void main(String[] args) {
                // {3,10} 是一个book元素，看成一个元素就行了。
                // 希望输出结果如下：
                // {[3,10]} {[4,20]}  {[1,5]}
                // {[ 3, 10 ], [ 4, 20 ]}   {[ 4, 20 ], [ 1, 5 ]}   {[ 3, 10 ], [ 1, 5 ]}
                // {[ 3, 10 ], [ 4, 20 ], [ 1, 5 ]}
                Integer[][] books1 = new Integer[][] { { 3, 10 }, { 4, 20 }, { 1, 5 } };
                List<Integer[]> bookCombination = new ArrayList<Integer[]>(Arrays.asList(books1));

                int num = bookCombination.size();
                while (num-- >= 0) {
                        List<List<Integer[]>> ret = helper(bookCombination, num);
                        for (List<Integer[]> combination : ret) {
                                for (Integer[] book : combination)
                                        System.out.printf(" %s", Arrays.deepToString(book));
                                System.out.println();
                        }
                        ;
                }
        }

}


【 在 callmebbser 的大作中提到: 】
: import java.util.Arrays;
: import java.util.TreeSet;
: public class CombinationTest {
: ...................
--
修改:iStudy FROM 58.37.127.*
FROM 58.37.127.*