你这个程序太精炼了，不太看得懂。。

用你的例子改了一下，结果不对，哪里错了

package test;

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

public class MySolution6 {

        private static List<List<Integer[]>> helper(List<Integer[]> bookSet,int curIndex,int level, 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 == (level+1)) {
                for (Integer[] book : bookSet)
                        {
                        bookSetCombination.add(book.clone());
                        }
                
                ret.add(bookSetCombination);
                        for (List<Integer[]> combination: ret) {
                                for (Integer[] book : combination)System.out.printf(" %s", Arrays.deepToString(book));
                                System.out.println();
                        };
                        return ret;    
            }
                
        for (int i = curIndex; i < bookSet.size(); i++) {

                bookSetCombination.add(bookSet.get(i));
                ret=helper(bookSet, i + 1, level + 1, num);
         }


        return ret;
        }

        public static void main(String[] args) {
                
                Integer[][] books1 = new Integer[][] { { 3, 10 }, { 4, 20 }, { 1,5 }, { 2, 40 },{3,40} };
                List<Integer[]> bookSet = new ArrayList<Integer[]>(Arrays.asList(books1));
                
                int num=bookSet.size();
                
                while(num-->=0) {
                        List<List<Integer[]>> ret = helper(bookSet,0,0,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.*