Java Program to calculate Unrank of permutation

Calculate the unrank of of permutaion:

	import java.util.Collection;
	import java.util.Collections;
	import java.util.LinkedList;
	import java.util.List;
	import java.util.stream.Collectors;
	public class unrank {
	public static int factorial(int number){
	if (number == 1 || number==0)
	return 1;
	return number * factorial(number-1);
	}
	public static String calculateUnrank(String test, int unranknum) {
	List<Character> answer = new LinkedList<>();
	List<Character> lst = new LinkedList<Character>();
	for (char a : test.toCharArray()) {
	lst.add(a);
	}
	Collections.sort(lst);
	while (lst.size() != 0) {
	int totalPermutation = factorial(lst.size());
	int eachblock = totalPermutation / lst.size();
	int dividend = unranknum / eachblock;
	unranknum = unranknum % eachblock;
	char value = lst.get(dividend);
	answer.add(Character.valueOf(value));
	lst.remove(Character.valueOf(value));
	}
	return answer.stream().map(String::valueOf).collect(Collectors.joining());
	}
	public static void main (String args[]){
	String test = "SPAIN";
	int unranknum = 115;
	String result = calculateUnrank(test,unranknum);
	System.out.println(result);
	}
	}

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