import java.util.ArrayList;

public class permutations {

public static void main(String[] args) {

String s = "abcd";

factorialp("",s);

// System.out.println(factorialpList("",s));

// System.out.println(factorialcount("",s));

}

private static int factorialcount(String p, String up) {

if(up.isEmpty()) {

return 1;

}

int count = 0;

char ch = up.charAt(0);

for (int i = 0; i <= p.length(); i++) {

String a = p.substring(0,i);

String b = p.substring(i,p.length());

count = count + factorialcount(a+ch+b,up.substring(1));

}

return count;

}

private static ArrayList<String> factorialpList(String p, String up) {

if(up.isEmpty()) {

ArrayList<String> list = new ArrayList<>();

list.add(p);

return list;

}

ArrayList<String> ans = new ArrayList<>();

char ch = up.charAt(0);

for (int i = 0; i <= p.length(); i++) {

String a = p.substring(0,i);

String b = p.substring(i,p.length());

ans.addAll(factorialpList(a+ch+b,up.substring(1)));

}

return ans;

}

private static void factorialp(String p, String up) {

if(up.isEmpty()) {

System.out.println(p);

return;

}

char ch = up.charAt(0);

for (int i = 0; i <= p.length(); i++) {

String a = p.substring(0,i);

String b = p.substring(i,p.length());

factorialp(a+ch+b,up.substring(1));

}

}

}