小小难题

[豪哥super叼]

输入:数组A[n,]正整数m
输出:对A[n]进行组合C(n m)的所有可能结果。

[自由自在_Yu]

参考：

public class Arrange {  
    public static void main(String[] args) {  
        Arrange arrange = new Arrange();  
        List<Character> data = new ArrayList<Character>();  
        data.add('a');  
        data.add('b');  
        data.add('c');  
        data.add('d');  
          
        //输出A(n,n)的全排列  
        for(int i = 1; i <= data.size(); i++)  
            arrange.arrangeSelect(data,new ArrayList<Character>(),i);  
  
    }  
      
    /** 
     * 计算A(n,k) 
     *  
     * @param data 
     * @param target 
     * @param k 
     */  
    public <E> void arrangeSelect(List<E> data,List<E> target, int k) {  
        List<E> copyData;  
        List<E> copyTarget;  
        if(target.size() == k) {  
            for(E i : target)   
                System.out.print(i);  
            System.out.println();  
        }  
      
        for(int i=0; i<data.size(); i++) {  
            copyData = new ArrayList<E>(data);  
            copyTarget = new ArrayList<E>(target);  
              
            copyTarget.add(copyData.get(i));  
            copyData.remove(i);  
              
            arrangeSelect(copyData, copyTarget,k);  
        }  
    }  
  
}  

a
b
c
d
ab
ac
ad
ba
bc
bd
ca
cb
cd
da
db
dc
abc
abd
acb
acd
adb
adc
bac
bad
bca
bcd
bda
bdc
cab
cad
cba
cbd
cda
cdb
dab
dac
dba
dbc
dca
dcb
abcd
abdc
acbd
acdb
adbc
adcb
bacd
badc
bcad
bcda
bdac
bdca
cabd
cadb
cbad
cbda
cdab
cdba
dabc
dacb
dbac
dbca
dcab
dcba

[豪哥super叼]

public class Math { //階乘 int c=1; public int factorial(int a) { for(int i=a;i>1;i--) { c=i*c; } return c; } } import java.util.ArrayList; import java.util.Scanner; public class Test { static Scanner sca,scb,scc; private static Scanner sca2; public static void main(String[] args) { Math a=new Math(); System.out.println("請輸入數組長度n："); sca2 = new Scanner(System.in); int number1=sca2.nextInt(); System.out.println("請輸入數組長度m："); int number2=scb.nextInt(); ArrayList al=new ArrayList(); for(int i=0;i<number1;i++) { System.out.println(a.factorial(number1)/((a.factorial(number1-number2)*a.factorial(number2)))); } }}

[豪哥super叼]

看了 你的代碼，表示臣妾看不懂 ，還是謝謝啦！

[yeyuanzhi2016]

学习了！！！