Find Unique Rank for a String

Problem Statement: For each String we need to assign a unique rank.

B will Have higher rank than A
Z Will have higher rank than B
Z will have higher rank than AA
KAMAL will be higher than AMIT (K>A)
KAWAL will be higher than KAMAL (W>A)
and so on

Solution: Assign a numeric value to each character in string and then add them in a way to create a rank.
Value assigned to characters (A is lowest)
A=0.01, b=0.02.. and so on


1. Loop The characters in string
1a. Assign Face weight to current character (A= 0.01, B= 0.02 etc)
1b. Assign Position Weight to current character (first char is multiple of 0.01, second of 0.0001 and so on)
1c. update totalweight by adding character weight calculated in 1a and 1b
2. Return totalweight

public static double getRank(String str)
char arr[]=str.toCharArray();
double rank=0;
double multiplier= 0.01;
for(int i=0;iAlgorithm Complexity:
Though if you look closely it might give impression of O(N) complexity, where N is characters in destination string. But as if are dealing with controlled input and string can be of average length 6-10 characters, we can easily confirm the algo to be of constant complexity.