csr1

public class csr1 {


    //csr1:given a string S and an Integer n <= the length of S,
    //generate all possible permutations of length n from the given string S.

    static String s ;
    static char[] c ;
    static int v  = 0 ;

    public static void permutations(String s, int n){
        csr1.s = s ;
        c = new char[n];
        v = 0;
        perm(0);
    }

    public static void perm(int n){
        if (n>=c.length){
            System.out.println(c);

        }
        else for (int i = 0; i < s.length(); i++) {
            if((v&(1<<i))==0){
            c[n] = s.charAt(i);
            v|=(1<<i);
            perm(n+1);
            v&=(~(1<<i));
            }
        }
    }

    public static void main(String[] args) {
        permutations("abc",2);

    }

}