public class solution {
    public static int[][] subsets(int input[],int index){
        if(index>=input.length){
            int[][] myAns = new int[1][0];
            return myAns;
        }
        int[][] smallAns = subsets(input,index+1);
        int[][] ans = new int[2*smallAns.length][];
        int k =0;
        int len = smallAns.length;
        for(int i=0;i<len;i++){
            ans[k] = new int[smallAns[i].length];
            for(int j=0;j<smallAns[i].length;j++){
                ans[k][j] = smallAns[i][j];
            }
            k++;
        }
        for(int i=0;i<len;i++){
            ans[k] = new int[smallAns[i].length+1];
            ans[k][0] = input[index];
            for(int j=1;j<=smallAns[i].length;j++){
                ans[k][j] = smallAns[i][j-1];
            }
            k++;
        }
        return ans;
    }
    public static int[][] subsets(int input[]) 
    {
        return subsets(input,0);
    }
}

这是我的答案。有效运作。它将以2d数组的形式返回输出。

public static void PrintSubsets(int[] input, boolean[] ifPrint, int 
             start, int remain){
    if(remain==0)
    {
      for(int i=0; i<ifPrint.length;i++)
        {
        if(ifPrint[i])
        System.out.print(input[i]+" ");   
        }
      System.out.print("\n");
    }
        else if(start+remain>input.length)
        return;

        else
       {
        for(int i = start; i<input.length; i++)
        {
         if(!ifPrint[i])    
          {
          ifPrint[i]=true;
          PrintSubsets(input, ifPrint, i+1, remain-1);
          ifPrint[i]=false;
                 }
               }
             }
`         }
   public static int[][] subsets(int input[]) {
    return subsets(input,0);
   }
   public static int[][] subsets(int input[], int StartIndex) {

    if(StartIndex==input.length)
    {
    return new int[1][0];
    }

    int SmallAns1[][]=subsets(input,StartIndex+1);
    int SmallAns2[][]=subsets(input,StartIndex+1);

    int ans[][]=new int[SmallAns1.length+SmallAns2.length][];
    int l=0;
    for(int i=0;i<SmallAns1.length;i++)
    {
        ans[l]=new int[SmallAns1[i].length + 1];
        ans[l][0] = input[StartIndex];
        for(int j=1;j<=SmallAns1[i].length;j++)
        {
            ans[l][j]=SmallAns1[i][j - 1];
        }
        l++;
    }

    for(int i=0;i<SmallAns2.length;i++)
    {
        ans[l]=new int[SmallAns2[i].length];
        for(int j=0;j<SmallAns2[i].length;j++)
        {
            ans[l][j]=SmallAns2[i][j];
        }
        l++;
    }        

    return ans;
    }