排列组合（Java实现）

public class Demo {

    public static void permutations(String[] str,int s,int e){
        if(s == e){
            for (int i = 0; i < str.length; i++){
                System.out.print(str[i] + " ");
            }
            System.out.println();
        }else{
            for(int i = s; i <= e;i++){
                swap(str,s,i);
                permutations(str,s + 1,e);
                swap(str,s,i);
            }
        }
    }



    public static void swap(String[] str ,int m ,int n){
        String temp = str[m];
        str[m] = str[n];
        str[n] = temp;

    }


    public static void main(String[] args) {
        String[] str = {"a","b","c"};
        permutations(str,0,str.length-1);
    }
}

a b c 
a c b 
b a c 
b c a 
c b a 
c a b