題目：
9名運動員參加比賽，需要分3組進行預賽。
有哪些分組的方案呢？
我們標記運動員為 A,B,C,… I
下面的程式列出了所有的分組方法。
該程式的正常輸出為：
ABC DEF GHI
ABC DEG FHI
ABC DEH FGI
ABC DEI FGH
ABC DFG EHI
ABC DFH EGI
ABC DFI EGH
ABC DGH EFI
….. (以下省略，總共560行)。

package com.ying.keepup;

public class fenxiaozu04 {
    public
 
 static String remain(int[] a)
    {
        String s = "";
        for(int i=0; i<a.length; i++){
            if(a[i] == 0) s += (char)(i+'A');
        }   
        return s;
    }

    public static void f(String s, int[] a)
    {
        for(int i=0; i<a.length; i++){
            if(a[i]==1) continue
 
;
            a[i] = 1;
            for(int j=i+1; j<a.length; j++){
                if(a[j]==1) continue;
                a[j]=1;
                for(int k=j+1; k<a.length; k++){
                    if(a[k]==1) continue;
                    a[k]=1;
                    System.out.println(s+" "
 
+(char)(i+'A')+(char)(j+'A')+(char)(k+'A')+" "+remain(a));  //填空位置
                    a[k]=0;
                }
                a[j]=0;
            }
            a[i] = 0;
        }
    }

    public static void main(String[] args)
    {
        int[] a = new int[9];       
        a[0] = 1;

        for(int b=1; b<a.length; b++){
            a[b] = 1;
            for(int c=b+1; c<a.length; c++){
                a[c] = 1;
                String s = "A" + (char)(b+'A') + (char)(c+'A');
                f(s,a);
                a[c] = 0;
            }
            a[b] = 0;
        }
    }
}

ABC DEF GHI
ABC DEG FHI
ABC DEH FGI
ABC DEI FGH
ABC DFG EHI
ABC DFH EGI
ABC DFI EGH
ABC DGH EFI
ABC DGI EFH
ABC DHI EFG
ABC EFG DHI
ABC EFH DGI
ABC EFI DGH
ABC EGH DFI
ABC EGI DFH
ABC EHI DFG
ABC FGH DEI
ABC FGI DEH
ABC FHI DEG
ABC GHI DEF
ABD CEF GHI
ABD CEG FHI
ABD CEH FGI
ABD CEI FGH
ABD CFG EHI
ABD CFH EGI
ABD CFI EGH
ABD CGH EFI
ABD CGI EFH
ABD CHI EFG
ABD EFG CHI
ABD EFH CGI
ABD EFI CGH
ABD EGH CFI
ABD EGI CFH
ABD EHI CFG
ABD FGH CEI
ABD FGI CEH
ABD FHI CEG
ABD GHI CEF
ABE CDF GHI
ABE CDG FHI
ABE CDH FGI
ABE CDI FGH
ABE CFG DHI
ABE CFH DGI
ABE CFI DGH
ABE CGH DFI
ABE CGI DFH
ABE CHI DFG
ABE DFG CHI
ABE DFH CGI
ABE DFI CGH
ABE DGH CFI
ABE DGI CFH
ABE DHI CFG
ABE FGH CDI
ABE FGI CDH
ABE FHI CDG
ABE GHI CDF
ABF CDE GHI
ABF CDG EHI
ABF CDH EGI
ABF CDI EGH
ABF CEG DHI
ABF CEH DGI
ABF CEI DGH
ABF CGH DEI
ABF CGI DEH
ABF CHI DEG
ABF DEG CHI
ABF DEH CGI
ABF DEI CGH
ABF DGH CEI
ABF DGI CEH
ABF DHI CEG
ABF EGH CDI
ABF EGI CDH
ABF EHI CDG
ABF GHI CDE
ABG CDE FHI
ABG CDF EHI
ABG CDH EFI
ABG CDI EFH
ABG CEF DHI
ABG CEH DFI
ABG CEI DFH
ABG CFH DEI
ABG CFI DEH
ABG CHI DEF
ABG DEF CHI
ABG DEH CFI
ABG DEI CFH
ABG DFH CEI
ABG DFI CEH
ABG DHI CEF
ABG EFH CDI
ABG EFI CDH
ABG EHI CDF
ABG FHI CDE
ABH CDE FGI
ABH CDF EGI
ABH CDG EFI
ABH CDI EFG
ABH CEF DGI
ABH CEG DFI
ABH CEI DFG
ABH CFG DEI
ABH CFI DEG
ABH CGI DEF
ABH DEF CGI
ABH DEG CFI
ABH DEI CFG
ABH DFG CEI
ABH DFI CEG
ABH DGI CEF
ABH EFG CDI
ABH EFI CDG
ABH EGI CDF
ABH FGI CDE
ABI CDE FGH
ABI CDF EGH
ABI CDG EFH
ABI CDH EFG
ABI CEF DGH
ABI CEG DFH
ABI CEH DFG
ABI CFG DEH
ABI CFH DEG
ABI CGH DEF
ABI DEF CGH
ABI DEG CFH
ABI DEH CFG
ABI DFG CEH
ABI DFH CEG
ABI DGH CEF
ABI EFG CDH
ABI EFH CDG
ABI EGH CDF
ABI FGH CDE
ACD BEF GHI
ACD BEG FHI
ACD BEH FGI
ACD BEI FGH
ACD BFG EHI
ACD BFH EGI
ACD BFI EGH
ACD BGH EFI
ACD BGI EFH
ACD BHI EFG
ACD EFG BHI
ACD EFH BGI
ACD EFI BGH
ACD EGH BFI
ACD EGI BFH
ACD EHI BFG
ACD FGH BEI
ACD FGI BEH
ACD FHI BEG
ACD GHI BEF
ACE BDF GHI
ACE BDG FHI
ACE BDH FGI
ACE BDI FGH
ACE BFG DHI
ACE BFH DGI
ACE BFI DGH
ACE BGH DFI
ACE BGI DFH
ACE BHI DFG
ACE DFG BHI
ACE DFH BGI
ACE DFI BGH
ACE DGH BFI
ACE DGI BFH
ACE DHI BFG
ACE FGH BDI
ACE FGI BDH
ACE FHI BDG
ACE GHI BDF
ACF BDE GHI
ACF BDG EHI
ACF BDH EGI
ACF BDI EGH
ACF BEG DHI
ACF BEH DGI
ACF BEI DGH
ACF BGH DEI
ACF BGI DEH
ACF BHI DEG
ACF DEG BHI
ACF DEH BGI
ACF DEI BGH
ACF DGH BEI
ACF DGI BEH
ACF DHI BEG
ACF EGH BDI
ACF EGI BDH
ACF EHI BDG
ACF GHI BDE
ACG BDE FHI
ACG BDF EHI
ACG BDH EFI
ACG BDI EFH
ACG BEF DHI
ACG BEH DFI
ACG BEI DFH
ACG BFH DEI
ACG BFI DEH
ACG BHI DEF
ACG DEF BHI
ACG DEH BFI
ACG DEI BFH
ACG DFH BEI
ACG DFI BEH
ACG DHI BEF
ACG EFH BDI
ACG EFI BDH
ACG EHI BDF
ACG FHI BDE
ACH BDE FGI
ACH BDF EGI
ACH BDG EFI
ACH BDI EFG
ACH BEF DGI
ACH BEG DFI
ACH BEI DFG
ACH BFG DEI
ACH BFI DEG
ACH BGI DEF
ACH DEF BGI
ACH DEG BFI
ACH DEI BFG
ACH DFG BEI
ACH DFI BEG
ACH DGI BEF
ACH EFG BDI
ACH EFI BDG
ACH EGI BDF
ACH FGI BDE
ACI BDE FGH
ACI BDF EGH
ACI BDG EFH
ACI BDH EFG
ACI BEF DGH
ACI BEG DFH
ACI BEH DFG
ACI BFG DEH
ACI BFH DEG
ACI BGH DEF
ACI DEF BGH
ACI DEG BFH
ACI DEH BFG
ACI DFG BEH
ACI DFH BEG
ACI DGH BEF
ACI EFG BDH
ACI EFH BDG
ACI EGH BDF
ACI FGH BDE
ADE BCF GHI
ADE BCG FHI
ADE BCH FGI
ADE BCI FGH
ADE BFG CHI
ADE BFH CGI
ADE BFI CGH
ADE BGH CFI
ADE BGI CFH
ADE BHI CFG
ADE CFG BHI
ADE CFH BGI
ADE CFI BGH
ADE CGH BFI
ADE CGI BFH
ADE CHI BFG
ADE FGH BCI
ADE FGI BCH
ADE FHI BCG
ADE GHI BCF
ADF BCE GHI
ADF BCG EHI
ADF BCH EGI
ADF BCI EGH
ADF BEG CHI
ADF BEH CGI
ADF BEI CGH
ADF BGH CEI
ADF BGI CEH
ADF BHI CEG
ADF CEG BHI
ADF CEH BGI
ADF CEI BGH
ADF CGH BEI
ADF CGI BEH
ADF CHI BEG
ADF EGH BCI
ADF EGI BCH
ADF EHI BCG
ADF GHI BCE
ADG BCE FHI
ADG BCF EHI
ADG BCH EFI
ADG BCI EFH
ADG BEF CHI
ADG BEH CFI
ADG BEI CFH
ADG BFH CEI
ADG BFI CEH
ADG BHI CEF
ADG CEF BHI
ADG CEH BFI
ADG CEI BFH
ADG CFH BEI
ADG CFI BEH
ADG CHI BEF
ADG EFH BCI
ADG EFI BCH
ADG EHI BCF
ADG FHI BCE
ADH BCE FGI
ADH BCF EGI
ADH BCG EFI
ADH BCI EFG
ADH BEF CGI
ADH BEG CFI
ADH BEI CFG
ADH BFG CEI
ADH BFI CEG
ADH BGI CEF
ADH CEF BGI
ADH CEG BFI
ADH CEI BFG
ADH CFG BEI
ADH CFI BEG
ADH CGI BEF
ADH EFG BCI
ADH EFI BCG
ADH EGI BCF
ADH FGI BCE
ADI BCE FGH
ADI BCF EGH
ADI BCG EFH
ADI BCH EFG
ADI BEF CGH
ADI BEG CFH
ADI BEH CFG
ADI BFG CEH
ADI BFH CEG
ADI BGH CEF
ADI CEF BGH
ADI CEG BFH
ADI CEH BFG
ADI CFG BEH
ADI CFH BEG
ADI CGH BEF
ADI EFG BCH
ADI EFH BCG
ADI EGH BCF
ADI FGH BCE
AEF BCD GHI
AEF BCG DHI
AEF BCH DGI
AEF BCI DGH
AEF BDG CHI
AEF BDH CGI
AEF BDI CGH
AEF BGH CDI
AEF BGI CDH
AEF BHI CDG
AEF CDG BHI
AEF CDH BGI
AEF CDI BGH
AEF CGH BDI
AEF CGI BDH
AEF CHI BDG
AEF DGH BCI
AEF DGI BCH
AEF DHI BCG
AEF GHI BCD
AEG BCD FHI
AEG BCF DHI
AEG BCH DFI
AEG BCI DFH
AEG BDF CHI
AEG BDH CFI
AEG BDI CFH
AEG BFH CDI
AEG BFI CDH
AEG BHI CDF
AEG CDF BHI
AEG CDH BFI
AEG CDI BFH
AEG CFH BDI
AEG CFI BDH
AEG CHI BDF
AEG DFH BCI
AEG DFI BCH
AEG DHI BCF
AEG FHI BCD
AEH BCD FGI
AEH BCF DGI
AEH BCG DFI
AEH BCI DFG
AEH BDF CGI
AEH BDG CFI
AEH BDI CFG
AEH BFG CDI
AEH BFI CDG
AEH BGI CDF
AEH CDF BGI
AEH CDG BFI
AEH CDI BFG
AEH CFG BDI
AEH CFI BDG
AEH CGI BDF
AEH DFG BCI
AEH DFI BCG
AEH DGI BCF
AEH FGI BCD
AEI BCD FGH
AEI BCF DGH
AEI BCG DFH
AEI BCH DFG
AEI BDF CGH
AEI BDG CFH
AEI BDH CFG
AEI BFG CDH
AEI BFH CDG
AEI BGH CDF
AEI CDF BGH
AEI CDG BFH
AEI CDH BFG
AEI CFG BDH
AEI CFH BDG
AEI CGH BDF
AEI DFG BCH
AEI DFH BCG
AEI DGH BCF
AEI FGH BCD
AFG BCD EHI
AFG BCE DHI
AFG BCH DEI
AFG BCI DEH
AFG BDE CHI
AFG BDH CEI
AFG BDI CEH
AFG BEH CDI
AFG BEI CDH
AFG BHI CDE
AFG CDE BHI
AFG CDH BEI
AFG CDI BEH
AFG CEH BDI
AFG CEI BDH
AFG CHI BDE
AFG DEH BCI
AFG DEI BCH
AFG DHI BCE
AFG EHI BCD
AFH BCD EGI
AFH BCE DGI
AFH BCG DEI
AFH BCI DEG
AFH BDE CGI
AFH BDG CEI
AFH BDI CEG
AFH BEG CDI
AFH BEI CDG
AFH BGI CDE
AFH CDE BGI
AFH CDG BEI
AFH CDI BEG
AFH CEG BDI
AFH CEI BDG
AFH CGI BDE
AFH DEG BCI
AFH DEI BCG
AFH DGI BCE
AFH EGI BCD
AFI BCD EGH
AFI BCE DGH
AFI BCG DEH
AFI BCH DEG
AFI BDE CGH
AFI BDG CEH
AFI BDH CEG
AFI BEG CDH
AFI BEH CDG
AFI BGH CDE
AFI CDE BGH
AFI CDG BEH
AFI CDH BEG
AFI CEG BDH
AFI CEH BDG
AFI CGH BDE
AFI DEG BCH
AFI DEH BCG
AFI DGH BCE
AFI EGH BCD
AGH BCD EFI
AGH BCE DFI
AGH BCF DEI
AGH BCI DEF
AGH BDE CFI
AGH BDF CEI
AGH BDI CEF
AGH BEF CDI
AGH BEI CDF
AGH BFI CDE
AGH CDE BFI
AGH CDF BEI
AGH CDI BEF
AGH CEF BDI
AGH CEI BDF
AGH CFI BDE
AGH DEF BCI
AGH DEI BCF
AGH DFI BCE
AGH EFI BCD
AGI BCD EFH
AGI BCE DFH
AGI BCF DEH
AGI BCH DEF
AGI BDE CFH
AGI BDF CEH
AGI BDH CEF
AGI BEF CDH
AGI BEH CDF
AGI BFH CDE
AGI CDE BFH
AGI CDF BEH
AGI CDH BEF
AGI CEF BDH
AGI CEH BDF
AGI CFH BDE
AGI DEF BCH
AGI DEH BCF
AGI DFH BCE
AGI EFH BCD
AHI BCD EFG
AHI BCE DFG
AHI BCF DEG
AHI BCG DEF
AHI BDE CFG
AHI BDF CEG
AHI BDG CEF
AHI BEF CDG
AHI BEG CDF
AHI BFG CDE
AHI CDE BFG
AHI CDF BEG
AHI CDG BEF
AHI CEF BDG
AHI CEG BDF
AHI CFG BDE
AHI DEF BCG
AHI DEG BCF
AHI DFG BCE
AHI EFG BCD