Java program to calculate rank of permutation.

1)  Rank program in java

	import java.util.Arrays;
	import java.util.LinkedList;
	import java.util.List;
	public class rank {
	public static int factorial(int number){
	if (number == 1 || number==0)
	return 1;
	return number * factorial(number-1);
	}
	public static int getRank(String test){
	char[] chararray = test.toCharArray();
	Arrays.sort(chararray);
	List<Character> lst = new LinkedList<>();
	for (char c :chararray){
	lst.add(c);
	}
	int sum = 0;
	int length = chararray.length;
	for(char c: test.toCharArray()){
	int index = lst.indexOf(c);
	sum = sum + (index)* factorial(length-1);
	length=length-1;
	lst.remove(Character.valueOf(c));
	}
	return sum;
	}
	public static void main(String args[]){
	String test = "BCA";
	int rank = getRank(test);
	System.out.println(rank);
	}
	}

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